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fis-gtm/sr_unix/mutex.c

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/****************************************************************
* *
* Copyright 2001, 2013 Fidelity Information Services, Inc *
* *
* This source code contains the intellectual property *
* of its copyright holder(s), and is made available *
* under a license. If you do not know the terms of *
* the license, please stop and do not read further. *
* *
****************************************************************/
/* GT.M Mutex Control */
#include "mdef.h"
#include "gtm_time.h" /* for time() */
#include "gtm_socket.h"
#include "gtm_string.h"
#include "gtm_stdlib.h"
#include "gtm_unistd.h"
#include "gtm_stdio.h"
#include <errno.h>
#include <sys/un.h>
#include <iotcp_select.h>
#if defined(__sparc) || defined(__hpux) || defined(__MVS__) || defined(__linux__) || defined(__CYGWIN__)
#include "gtm_limits.h"
#else
#include <sys/limits.h>
#endif
#include "aswp.h"
#include "gdsroot.h"
#include "gtm_facility.h"
#include "fileinfo.h"
#include "gdsbt.h"
#include "gdsfhead.h"
#include "lockconst.h"
#include "interlock.h"
#include "filestruct.h"
#include "io.h"
#include "jnl.h"
#include "gdsbgtr.h"
#include "mutex.h"
#include "relqueopi.h"
#include "eintr_wrappers.h"
#include "send_msg.h"
#include "is_proc_alive.h"
#include "compswap.h"
#include "gtmsecshr.h"
#include "rel_quant.h"
#include "add_inter.h"
#include "mutex_deadlock_check.h"
#include "gt_timer.h"
#include "gtmio.h"
#include "gtm_c_stack_trace.h"
#ifdef DEBUG
#include "wbox_test_init.h"
#include "repl_msg.h" /* needed by gtmsource.h */
#include "gtmsource.h" /* required for jnlpool GBLREF */
#endif
#define QUANT_RETRY 10000
#define QUEUE_RETRY 255
#ifdef MUTEX_MSEM_WAKE
#define MUTEX_MAX_HEARTBEAT_WAIT 2 /* so that total wait for both select and msem wait will be the same */
#define MUTEX_LCKALERT_PERIOD 4
#endif
/* The following CAREFUL_* macros invoke the corresponding * macros except in the case csa->hdr is NULL.
* This is possible if the csa corresponds to the journal pool where there is no notion of a db hdr.
* In that case, we skip invoking the * macros.
*/
#define CAREFUL_SET_TRACEABLE_VAR(CSA, VALUE) \
{ \
sgmnt_data_ptr_t lcl_csd; \
\
lcl_csd = CSA->hdr; \
assert((NULL != lcl_csd) \
|| (CSA == &FILE_INFO(jnlpool.jnlpool_dummy_reg)->s_addrs)); \
if (NULL != lcl_csd) \
SET_TRACEABLE_VAR(CSA->nl->wc_blocked, TRUE); \
}
#define CAREFUL_BG_TRACE_PRO_ANY(CSA, EVENT) \
{ \
sgmnt_data_ptr_t lcl_csd; \
\
lcl_csd = CSA->hdr; \
assert((NULL != lcl_csd) \
|| (CSA == &FILE_INFO(jnlpool.jnlpool_dummy_reg)->s_addrs)); \
if (NULL != lcl_csd) \
BG_TRACE_PRO_ANY(CSA, EVENT); \
}
GBLREF pid_t process_id;
GBLREF int process_exiting;
GBLREF uint4 image_count;
GBLREF int num_additional_processors;
#ifdef MUTEX_MSEM_WAKE
GBLREF volatile uint4 heartbeat_counter;
# ifdef POSIX_MSEM
static sem_t *mutex_wake_msem_ptr = NULL;
# else
static msemaphore *mutex_wake_msem_ptr = NULL;
# endif
static mutex_que_entry_ptr_t msem_slot;
#else
GBLREF int mutex_sock_fd;
GBLREF fd_set mutex_wait_on_descs;
#endif
GBLREF uint4 mutex_per_process_init_pid;
#ifdef DEBUG
GBLREF jnlpool_addrs jnlpool;
GBLREF boolean_t in_mu_rndwn_file;
#endif
GBLREF jnl_gbls_t jgbl;
DECLARE_MUTEX_TRACE_CNTRS
DECLARE_MUTEX_TEST_SIGNAL_FLAG
static boolean_t woke_self;
static boolean_t woke_none;
static unsigned short next_rand[3];
static int optimistic_attempts;
static int mutex_expected_wake_instance = 0;
static enum cdb_sc mutex_wakeup(mutex_struct_ptr_t addr);
void mutex_salvage(gd_region *reg);
error_def(ERR_MUTEXERR);
error_def(ERR_MUTEXFRCDTERM);
error_def(ERR_MUTEXLCKALERT);
error_def(ERR_ORLBKINPROG);
error_def(ERR_TEXT);
error_def(ERR_WCBLOCKED);
/*
* General:
* Uses compare-and-swap logic to obtain/release a semaphore
* in shared memory.
*
* Interface:
* void gtm_mutex_init(reg, n, crash)
* Initialize mutex structure for region reg with n
* queue slots. If crash is TRUE, then this is a "crash"
* reinitialization; otherwise, it's a "clean" initialization.
*
* enum cdb_sc mutex_lockw(reg, mutex_spin_parms, seq)
* Write access to mutex for region reg
*
* enum cdb_sc mutex_lockwim(reg, mutex_spin_parms, seq)
* Write access for region reg; if cannot lock,
* immediately return cdb_sc_nolock
*
* enum cdb_sc mutex_unlockw(reg, seq);
* Unlock write access for region reg
*
* For routines taking the seq argument, if seq != crash count,
* return cdb_sc_critreset.
*
*
* Mutex structure must be quadword aligned
*
*
* Mutex structure :
*
* ---------------------------------
* | semaphore |
* ---------------------------------
* | crash count |
* ---------------------------------
* | stuckexec | <-UNIX only
* --------------------------------
* | # of que slots |
* --------------------------------
* |_ fl waiting process que head _|
* |_ bl _|
* |_ global_latch _|
* ---------------------------------
* |_ fl unused slots queue head _|
* |_ bl _|
* |_ global_latch _|
* ---------------------------------
* |_ fl first queue entry _|
* |_ bl _|
* |_ pid _|
* | super_crit [CCP use only]^ |
* ---------------------------------
* |_ fl second queue entry _|
* |_ bl _|
* |_ pid _|
* | super_crit [CCP use only]^ |
* ---------------------------------
* : : : : :
* ---------------------------------
* |_ fl last queue entry _|
* |_ bl _|
* |_ pid _|
* | super_crit [CCP use only]^ |
* ---------------------------------
*
* ^Note: only one entry at a time (at the head of the
* waiting process queue) will ever use "super_crit".
* CCP is used in VMS only - 03/11/98
* 07-31-2002 se: super-crit is not used at all anymore. Comments are left for historical purposes.
*
* Fields may be interspersed with fillers for alignment purposes.
*/
static void clean_initialize(mutex_struct_ptr_t addr, int n, bool crash)
{
mutex_que_entry_ptr_t q_free_entry;
# if defined(MUTEX_MSEM_WAKE) && !defined(POSIX_MSEM)
msemaphore *status;
# endif
assert(n > 0);
addr->queslots = n;
/* Initialize the waiting process queue to be empty */
addr->prochead.que.fl = addr->prochead.que.bl = 0;
SET_LATCH_GLOBAL(&addr->prochead.latch, LOCK_AVAILABLE);
/* Initialize the free queue to be empty */
addr->freehead.que.fl = addr->freehead.que.bl = 0;
SET_LATCH_GLOBAL(&addr->freehead.latch, LOCK_AVAILABLE);
/* Clear the first free entry */
q_free_entry = (mutex_que_entry_ptr_t)((sm_uc_ptr_t)&addr->freehead + SIZEOF(mutex_que_head));
q_free_entry->que.fl = q_free_entry->que.bl = 0;
q_free_entry->pid = 0;
q_free_entry->super_crit = (void *)NULL;
q_free_entry->mutex_wake_instance = 0;
while (n--)
{
# ifdef MUTEX_MSEM_WAKE
# ifdef POSIX_MSEM
if (-1 == sem_init(&q_free_entry->mutex_wake_msem, TRUE, 0)) /* Shared lock with no initial resources (locked) */
# else
if ((NULL == (status = msem_init(&q_free_entry->mutex_wake_msem, MSEM_LOCKED))) || ((msemaphore *)-1 == status))
# endif
rts_error(VARLSTCNT(7) ERR_MUTEXERR, 0, ERR_TEXT, 2,
RTS_ERROR_TEXT("Error with mutex wait memory semaphore initialization"), errno);
# endif
/* Initialize fl,bl links to 0 before INSQTI as it (gtm_insqti in relqueopi.c) asserts this */
DEBUG_ONLY(((que_ent_ptr_t)q_free_entry)->fl = 0;)
DEBUG_ONLY(((que_ent_ptr_t)q_free_entry)->bl = 0;)
if (INTERLOCK_FAIL == INSQTI((que_ent_ptr_t)q_free_entry++, (que_head_ptr_t)&addr->freehead))
rts_error(VARLSTCNT(6) ERR_MUTEXERR, 0, ERR_TEXT, 2,
RTS_ERROR_TEXT("Interlock instruction failure in mutex initialize"));
}
SET_LATCH_GLOBAL(&addr->semaphore, LOCK_AVAILABLE);
SET_LATCH_GLOBAL((global_latch_t *)&addr->stuckexec, LOCK_AVAILABLE);
if (!crash)
{
SET_LATCH(&addr->crashcnt, 0);
SET_LATCH_GLOBAL(&addr->crashcnt_latch, LOCK_AVAILABLE);
}
return;
}
static void crash_initialize(mutex_struct_ptr_t addr, int n, bool crash)
{
/*
* mutex_wake_proc() is not declared here because its return value
* is left unspecified in its definition (see mutex_wake_proc.c)
*/
mutex_que_entry_ptr_t next_entry;
INCR_CNT(&addr->crashcnt, &addr->crashcnt_latch);
addr->freehead.que.fl = addr->freehead.que.bl = 0;
next_entry = (mutex_que_entry_ptr_t)&addr->prochead;
do
{
if (0 == next_entry->que.fl)
{
/* Wait queue empty; do a clean initialization */
clean_initialize(addr, n, crash);
return;
}
next_entry = (mutex_que_entry_ptr_t)((sm_uc_ptr_t)next_entry + next_entry->que.fl);
if (next_entry <= (mutex_que_entry_ptr_t)&addr->prochead ||
next_entry >= (mutex_que_entry_ptr_t)&addr->prochead + n + 1 ||
(0 != ((INTPTR_T)next_entry & (SIZEOF(mutex_que_entry) - 1))))
{
/*
* next_entry == &addr->prochead => loop is done;
* next_entry below queue head => queue is corrupt;
* next_entry above queue top => queue is corrupt;
* next_entry is not (SIZEOF(queue) entry)-byte
* aligned => queue is corrupt ...
* ... in all cases do a clean initialization
*/
clean_initialize(addr, n, crash);
return;
}
/* Wake up process */
if (next_entry->pid != process_id)
# ifdef MUTEX_MSEM_WAKE
mutex_wake_proc(&next_entry->mutex_wake_msem);
# else
mutex_wake_proc((sm_int_ptr_t)&next_entry->pid, next_entry->mutex_wake_instance);
# endif
} while (TRUE);
}
static enum cdb_sc mutex_long_sleep(mutex_struct_ptr_t addr, mutex_lock_t mutex_lock_type, sgmnt_addrs *csa)
{
enum cdb_sc status;
boolean_t wakeup_status;
# ifdef MUTEX_MSEM_WAKE
uint4 bad_heartbeat;
# else
struct timeval timeout;
int timeout_threshold;
struct sockaddr_un mutex_woke_me_proc;
GTM_SOCKLEN_TYPE mutex_woke_me_proc_len;
mutex_wake_msg_t mutex_wake_msg[2];
int sel_stat;
ssize_t nbrecvd;
int timeout_intr_slpcnt;
long timeout_val;
# endif
# ifdef DEBUG
if (gtm_white_box_test_case_enabled
&& (WBTEST_SENDTO_EPERM == gtm_white_box_test_case_number))
{
FPRINTF(stderr, "MUPIP BACKUP is about to start long sleep\n");
}
# endif
if (LOCK_AVAILABLE == addr->semaphore.u.parts.latch_pid && ++optimistic_attempts <= MUTEX_MAX_OPTIMISTIC_ATTEMPTS)
{
MUTEX_DPRINT2("%d: Nobody in crit (II) wake procs\n", process_id);
MUTEX_TRACE_CNTR(mutex_trc_mutex_slp_fn_noslp);
status = mutex_wakeup(addr);
if ((cdb_sc_normal == status) && (woke_self || woke_none))
return (cdb_sc_normal);
else if (cdb_sc_dbccerr == status)
return (cdb_sc_dbccerr);
}
optimistic_attempts = 0;
do
{
# ifdef MUTEX_MSEM_WAKE
/* My msemaphore is already used by another process.
* In other words, I was woken up, but missed my wakeup call.
* I should return immediately.
*/
if (msem_slot->pid != process_id)
wakeup_status = TRUE;
else
{
bad_heartbeat = 0;
/*
* the check for EINTR below is valid and should not be converted to an EINTR
* wrapper macro, because another condition is checked for the while loop.
*/
while (!(wakeup_status = (0 == MSEM_LOCKW(mutex_wake_msem_ptr))))
{
if (EINTR == errno)
{
if (bad_heartbeat) /* to save memory reference and calc on fast path */
{
if (bad_heartbeat < heartbeat_counter)
{
MUTEX_DPRINT3("%d: msem sleep done, heartbeat_counter = %d\n",
process_id, heartbeat_counter);
break;
}
MUTEX_DPRINT3("%d: msem sleep continue, heartbeat_counter = %d\n",
process_id, heartbeat_counter);
} else
bad_heartbeat = heartbeat_counter + MUTEX_MAX_HEARTBEAT_WAIT - 1;
/* -1 since we were interrupted this time */
} else
rts_error(VARLSTCNT(7) ERR_MUTEXERR, 0, ERR_TEXT, 2,
RTS_ERROR_TEXT("Error with mutex wake msem"), errno);
}
/* wakeup_status is set to true, if I was able to lock...somebody woke me up;
* wakeup_status is set to false, if I timed out and should go to recovery.
*/
}
# else
do
{
timeout.tv_sec = MUTEX_CONST_TIMEOUT_VAL;
timeout.tv_usec = (gtm_tv_usec_t)(nrand48(next_rand) & ((1U << MUTEX_NUM_WAIT_BITS) - 1)) + 1;
timeout_val = timeout.tv_sec * ONE_MILLION + timeout.tv_usec;
/*
* Can add backoff logic here to increase the timeout
* as the number of attempts increase
*/
timeout_intr_slpcnt = MUTEX_INTR_SLPCNT;
MUTEX_DPRINT4("%d: Sleeping for %d s %d us\n", process_id, timeout.tv_sec, timeout.tv_usec);
FD_SET(mutex_sock_fd, &mutex_wait_on_descs);
MUTEX_TRACE_CNTR(mutex_trc_slp);
/*
* the check for EINTR below is valid and should not be converted to an EINTR
* wrapper macro, since it might be a timeout.
*/
while (-1 == (sel_stat =
select(mutex_sock_fd + 1, &mutex_wait_on_descs, (fd_set *)NULL, (fd_set *)NULL, &timeout)))
{
if (EINTR == errno)
{ /* somebody interrupted me, reduce the timeout by half and continue */
MUTEX_TRACE_CNTR(mutex_trc_slp_intr);
if (!(timeout_intr_slpcnt--)) /* Assume timed out */
{
sel_stat = 0;
MUTEX_TRACE_CNTR(mutex_trc_intr_tmout);
break;
}
} else
rts_error(VARLSTCNT(5) ERR_TEXT, 2,
RTS_ERROR_TEXT("Error with mutex select. Running in degraded mode"), errno);
timeout_val >>= 1;
timeout.tv_sec = timeout_val / ONE_MILLION;
timeout.tv_usec = (gtm_tv_usec_t)(timeout_val % ONE_MILLION);
MUTEX_DPRINT4("%d: Interrupted select, new timeout %d s %d us\n", process_id, timeout.tv_sec,
timeout.tv_usec);
/* the next line deals with the case that an interrupted select has changed mutex_wait_on_descs */
FD_SET(mutex_sock_fd, &mutex_wait_on_descs);
MUTEX_TRACE_CNTR(mutex_trc_slp);
}
if (1 == sel_stat) /* Somebody woke me up */
{
mutex_woke_me_proc_len = SIZEOF(struct sockaddr_un);
RECVFROM_SOCK(mutex_sock_fd, (void *)&mutex_wake_msg[0], SIZEOF(mutex_wake_msg), 0,
(struct sockaddr *)&mutex_woke_me_proc,
(GTM_SOCKLEN_TYPE *)&mutex_woke_me_proc_len, nbrecvd);
if (SIZEOF(mutex_wake_msg) == nbrecvd) /* Drained out both old and new wake messages */
{
MUTEX_TRACE_CNTR(mutex_trc_slp_wkup);
MUTEX_TRACE_CNTR(mutex_trc_pgybckd_dlyd_wkup);
MUTEX_DPRINT3("%d: %d woke me up, drained delayed message too\n", process_id,
mutex_wake_msg[1].pid);
wakeup_status = TRUE;
break;
}
if (BIN_TOGGLE(mutex_expected_wake_instance) == mutex_wake_msg[0].mutex_wake_instance)
{
MUTEX_DPRINT3("%d: %d woke me up\n", process_id, mutex_wake_msg[0].pid);
MUTEX_TRACE_CNTR(mutex_trc_slp_wkup);
wakeup_status = TRUE;
break;
} /* else, old wake msg, ignore */
MUTEX_DPRINT3("%d: %d sent me delayed wake msg\n", process_id, mutex_wake_msg[0].pid);
MUTEX_TRACE_CNTR(mutex_trc_xplct_dlyd_wkup);
} else if (0 == sel_stat) /* Timed out */
{
MUTEX_DPRINT2("%d: Sleep done, go wake others\n", process_id);
MUTEX_TRACE_CNTR(mutex_trc_slp_tmout);
wakeup_status = FALSE;
break;
}
} while (TRUE);
# endif
/*
* If I was woken up and am a writer, others are blocking on
* me. So, I shall try to get the lock NOW
*/
if (wakeup_status)
{
if (MUTEX_LOCK_WRITE == mutex_lock_type)
return (cdb_sc_normal);
} else
mutex_deadlock_check(addr, csa); /* Timed out: See if any deadlocks and fix if detected */
status = mutex_wakeup(addr); /* Timed out or reader. In case
* of reader this causes
* accelerated wakeup of readers
* in the queue */
if (cdb_sc_dbccerr == status)
return (cdb_sc_dbccerr);
/* else status is cdb_sc_normal */
if (wakeup_status || woke_self || woke_none)
return (cdb_sc_normal);
/*
* There are others above me in the queue or I missed my
* wakeup call. In the latter case, select or msem_lock will return
* immediately and there won't be further sleeps.
*/
} while (TRUE);
}
static enum cdb_sc mutex_sleep(sgmnt_addrs *csa, mutex_lock_t mutex_lock_type)
{
/* Insert this process at the tail of the wait queue and hibernate */
mutex_struct_ptr_t addr;
mutex_que_entry_ptr_t free_slot;
int redo_cntr;
int queue_retry_counter_remq,
quant_retry_counter_remq,
queue_retry_counter_insq,
quant_retry_counter_insq;
# ifdef MUTEX_MSEM_WAKE
int rc;
# endif
addr = csa->critical;
MUTEX_TRACE_CNTR(mutex_trc_mutex_slp_fn);
MUTEX_DPRINT2("%d: In Mutex Sleep\n", process_id);
if (LOCK_AVAILABLE == addr->semaphore.u.parts.latch_pid) /* there is nobody in crit */
{
/*
* The above condition is an optimistic check to speed
* things up by not letting a process sleep.
* In an n-way SMP, there is a possibility that n processes
* (atleast one writer) might run in a lock-step manner
* testing the above condition almost at the same time and
* deciding that nobody is in crit. This might go on till
* atleast one of them grabs crit, or lock attempts cross a
* threshold (leading to recovery). This is not desired. To
* avoid such a scenario, we test the number of times we have
* run into this situation and force ourselves to sleep
*/
if (++optimistic_attempts < MUTEX_MAX_OPTIMISTIC_ATTEMPTS)
{
MUTEX_DPRINT2("%d: Nobody in crit (I) wake procs\n", process_id);
MUTEX_TRACE_CNTR(mutex_trc_mutex_slp_fn_noslp);
return (mutex_wakeup(addr));
}
}
redo_cntr = 0;
quant_retry_counter_remq = QUANT_RETRY;
do
{
queue_retry_counter_remq = QUEUE_RETRY;
do
{
free_slot = (mutex_que_entry_ptr_t)REMQHI((que_head_ptr_t)&addr->freehead);
# ifdef MUTEX_MSEM_WAKE
msem_slot = free_slot;
# endif
if (!process_exiting && (NULL != free_slot) && (mutex_que_entry_ptr_t)INTERLOCK_FAIL != free_slot)
{
free_slot->pid = process_id;
free_slot->mutex_wake_instance = mutex_expected_wake_instance;
# ifdef MUTEX_MSEM_WAKE
mutex_wake_msem_ptr = &free_slot->mutex_wake_msem;
/* this loop makes sure that the msemaphore is locked initially
* before the process goes to long sleep
*/
do
{
rc = MSEM_LOCKNW(mutex_wake_msem_ptr);
} while (-1 == rc && EINTR == errno);
# endif
/*
* Significance of mutex_wake_instance field :
* -----------------------------------------
* After queueing itself, a process
* might go to sleep (select call in
* mutex_long_sleep) awaiting a wakeup message
* or a timeout. It is possible that a wakeup
* message might arrive after timeout. In this
* case, a later attempt at waiting for a
* wakeup message will falsely succeed on an
* old wakeup message. We use the
* mutex_wake_instance field (value 0 or 1)
* to distinguish between an old and a new
* wakeup message. Since at any given time
* there is atmost one entry in the queue for
* a process, the only values we need for
* mutex_wake_instance are 0 and 1.
*/
mutex_expected_wake_instance = BIN_TOGGLE(mutex_expected_wake_instance);
quant_retry_counter_insq = QUANT_RETRY;
do
{
queue_retry_counter_insq = QUEUE_RETRY;
do
{
if (INTERLOCK_FAIL !=
INSQTI((que_ent_ptr_t)free_slot, (que_head_ptr_t)&addr->prochead))
{
MUTEX_DPRINT3("%d: Inserted %d into wait queue\n", process_id,
free_slot->pid);
return (mutex_long_sleep(addr, mutex_lock_type, csa));
}
} while (--queue_retry_counter_insq);
if (!(--quant_retry_counter_insq))
return (cdb_sc_dbccerr); /* Too many failures */
rel_quant();
} while (quant_retry_counter_insq);
continue;
}
if ((mutex_que_entry_ptr_t)INTERLOCK_FAIL == free_slot)
{
/* secondary interlock failed on an attempt to
* remove an entry from the free queue */
redo_cntr = 0;
continue;
}
if ((mutex_que_entry_ptr_t)NULL == free_slot)
{
/* Record queue full event in db file header if applicable.
* Take care not to do it for jnlpool which has no concept of a db cache.
* In that case csa->hdr is NULL so use CAREFUL_BG_TRACE_PRO_ANY macro.
*/
CAREFUL_BG_TRACE_PRO_ANY(csa, mutex_queue_full);
MUTEX_DPRINT2("%d: Free Queue full\n", process_id);
/*
* When I can't find a free slot in the queue
* repeatedly, it means that there is no
* progress in the system. A recovery attempt
* might be warranted in this scenario. The
* trick is to return cdb_sc_normal which in
* turn causes another spin-loop initiation (or
* recovery when implemented).
* The objective of mutex_sleep is achieved
* (partially) in that sleep is done, though
* queueing isn't.
*/
} else
assert(process_exiting); /* timers might be off, but this adds CPU load at an awkward time */
MICROSEC_SLEEP(ONE_MILLION - 1); /* Wait a second, then try again */
mutex_deadlock_check(addr, csa);
if (++redo_cntr < MUTEX_MAX_WAIT_FOR_PROGRESS_CNTR)
break;
return (cdb_sc_normal);
} while (--queue_retry_counter_remq);
if (redo_cntr)
quant_retry_counter_remq = QUANT_RETRY + 1;
else
rel_quant();
} while (--quant_retry_counter_remq);
return (cdb_sc_dbccerr);
}
static enum cdb_sc mutex_wakeup(mutex_struct_ptr_t addr)
{
mutex_que_entry_ptr_t free_entry;
int queue_retry_counter_remq,
quant_retry_counter_remq,
queue_retry_counter_insq,
quant_retry_counter_insq;
uint4 wake_this_pid;
int wake_instance;
woke_self = FALSE;
woke_none = TRUE;
quant_retry_counter_remq = QUANT_RETRY;
do
{
queue_retry_counter_remq = QUEUE_RETRY;
do
{
free_entry = (mutex_que_entry_ptr_t)REMQHI((que_head_ptr_t)&addr->prochead);
if ((mutex_que_entry_ptr_t)NULL != free_entry &&
(mutex_que_entry_ptr_t)INTERLOCK_FAIL != free_entry)
{
quant_retry_counter_insq = QUANT_RETRY;
wake_this_pid = free_entry->pid;
wake_instance = free_entry->mutex_wake_instance;
# ifdef MUTEX_MSEM_WAKE
/*
* In case of msem wakeup, the msem has to be
* unlocked before returning free_entry to
* free queue, or else another process might
* use the same msem (in free_entry) for its
* sleep.
*/
if (wake_this_pid != process_id)
mutex_wake_proc(&free_entry->mutex_wake_msem);
else
woke_self = TRUE;
/* This makes this entry not belong to any process before
* inserting it into the free queue.
*/
free_entry->pid = 0;
# endif
do
{
queue_retry_counter_insq = QUEUE_RETRY;
do
{
if (INTERLOCK_FAIL !=
INSQTI((que_ent_ptr_t)free_entry, (que_head_ptr_t)&addr->freehead))
{
MUTEX_DPRINT3("%d: Waking up %d\n", process_id, wake_this_pid);
woke_none = FALSE;
if (wake_this_pid != process_id)
{
MUTEX_TRACE_CNTR(mutex_trc_crit_wk);
# ifndef MUTEX_MSEM_WAKE
mutex_wake_proc((sm_int_ptr_t)&wake_this_pid, wake_instance);
# endif
} else
{
/* With
* msem wake,
* this can
* never
* happen */
woke_self = TRUE;
}
return (cdb_sc_normal); /* No more wakes */
}
} while (--queue_retry_counter_insq);
if (!(--quant_retry_counter_insq))
{
# ifndef MUTEX_MSEM_WAKE
if (wake_this_pid != process_id)
mutex_wake_proc((sm_int_ptr_t)&wake_this_pid, wake_instance);
# endif
/* Too many failures */
return (cdb_sc_dbccerr);
} else
rel_quant();
} while (quant_retry_counter_insq);
} else if ((mutex_que_entry_ptr_t)NULL == free_entry)
{
/* Empty wait queue */
MUTEX_DPRINT2("%d: Empty wait queue\n", process_id);
return (cdb_sc_normal);
} /* else secondary interlock failed */
} while (--queue_retry_counter_remq);
if (!(--quant_retry_counter_remq))
return (cdb_sc_dbccerr); /* Too many queue failures */
else
rel_quant();
} while (quant_retry_counter_remq);
return (cdb_sc_dbccerr); /* This will never get executed, added to make compiler happy */
}
void gtm_mutex_init(gd_region *reg, int n, bool crash)
{
if (!crash)
clean_initialize((&FILE_INFO(reg)->s_addrs)->critical, n, crash);
else
crash_initialize((&FILE_INFO(reg)->s_addrs)->critical, n, crash);
return;
}
static enum cdb_sc write_lock_spin(gd_region *reg,
mutex_spin_parms_ptr_t mutex_spin_parms,
int crash_count,
int attempt_recovery,
mutex_lock_t mutex_lock_type)
{
int write_sleep_spin_count, write_hard_spin_count;
sgmnt_addrs *csa;
mutex_struct_ptr_t addr;
# ifdef MUTEX_REAL_SLEEP
int micro_sleep_time;
# endif
csa = &FILE_INFO(reg)->s_addrs;
assert(!csa->now_crit);
addr = csa->critical;
write_sleep_spin_count = 0;
write_hard_spin_count = 0;
do
{
do
{
if (crash_count != addr->crashcnt)
return (cdb_sc_critreset);
if (GET_SWAPLOCK(&addr->semaphore))
{
csa->critical->crit_cycle++;
MUTEX_DPRINT3("%d: Write %sACQUIRED\n", process_id,
(MUTEX_LOCK_WRITE == mutex_lock_type) ? "" : "IMMEDIATE ");
MUTEX_TEST_SIGNAL_HERE("WRTLCK NOW CRIT\n", FALSE);
csa->now_crit = TRUE;
MUTEX_TEST_SIGNAL_HERE("WRTLCK SUCCESS\n", FALSE);
return (cdb_sc_normal);
} else if (attempt_recovery)
{
mutex_salvage(reg);
attempt_recovery = FALSE;
}
if (!write_hard_spin_count) /* save memory reference on fast path */
write_hard_spin_count = num_additional_processors ? mutex_spin_parms->mutex_hard_spin_count : 1;
} while (--write_hard_spin_count);
/* Sleep for a very short duration */
# ifdef MUTEX_TRACE
if (MUTEX_LOCK_WRITE == mutex_lock_type)
MUTEX_TRACE_CNTR(mutex_trc_wt_short_slp);
else
MUTEX_TRACE_CNTR(mutex_trc_wtim_short_slp);
# endif
# ifdef MUTEX_REAL_SLEEP
micro_sleep_time = (nrand48(next_rand) & mutex_spin_parms->mutex_spin_sleep_mask) + 1;
assert(micro_sleep_time < ONE_MILLION);
assert(FALSE == csa->now_crit);
MICROSEC_SLEEP(micro_sleep_time);
# else
rel_quant();
# endif
if (!write_sleep_spin_count) /* save memory reference on fast path */
write_sleep_spin_count = mutex_spin_parms->mutex_sleep_spin_count;
} while (--write_sleep_spin_count);
MUTEX_DPRINT4("%d: Could not acquire WRITE %sLOCK, held by %d\n", process_id,
(MUTEX_LOCK_WRITE == mutex_lock_type) ? "" : "IMMEDIATE ", addr->semaphore.u.parts.latch_pid);
return (cdb_sc_nolock);
}
static enum cdb_sc mutex_lock(gd_region *reg,
mutex_spin_parms_ptr_t mutex_spin_parms,
int crash_count,
mutex_lock_t mutex_lock_type)
{
boolean_t try_recovery;
enum cdb_sc status;
int lock_attempts;
latch_t local_crit_cycle;
pid_t in_crit_pid;
sgmnt_addrs *csa;
time_t curr_time;
uint4 curr_time_uint4, next_alert_uint4;
csa = &FILE_INFO(reg)->s_addrs;
/* Check that "mutex_per_process_init" has happened before we try to grab crit and that it was done with our current
* pid (i.e. ensure that even in the case where parent did the mutex init with its pid and did a fork, the child process
* has done a reinitialization with its pid). The only exception is if we are in "mu_rndwn_file" in which case we
* know for sure there is no other pid accessing the database shared memory.
*/
assert((MUTEX_LOCK_WRITE_IMMEDIATE == mutex_lock_type) || (MUTEX_LOCK_WRITE == mutex_lock_type));
assert(mutex_per_process_init_pid == process_id || (0 == mutex_per_process_init_pid) && in_mu_rndwn_file);
MUTEX_TRACE_CNTR((MUTEX_LOCK_WRITE == mutex_lock_type) ? mutex_trc_lockw : mutex_trc_lockwim);
optimistic_attempts = 0;
lock_attempts = 0;
local_crit_cycle = 0; /* this keeps us from doing a MUTEXLCKALERT on the first cycle in case the time latch is stale */
try_recovery = jgbl.onlnrlbk; /* salvage lock the first time if we are online rollback thereby reducing unnecessary waits */
do
{
in_crit_pid = csa->nl->in_crit;
lock_attempts++;
MUTEX_TRACE_CNTR(mutex_trc_w_atmpts);
status = write_lock_spin(reg, mutex_spin_parms, crash_count, try_recovery, mutex_lock_type);
if ((cdb_sc_normal == status) || (MUTEX_LOCK_WRITE_IMMEDIATE == mutex_lock_type) || (cdb_sc_critreset == status))
return (status);
try_recovery = FALSE; /* only try recovery once per MUTEXLCKALERT */
assert(cdb_sc_nolock == status);
time(&curr_time);
assert(MAXUINT4 > curr_time);
curr_time_uint4 = (uint4)curr_time;
next_alert_uint4 = csa->critical->stuckexec.cas_time;
if (curr_time_uint4 > next_alert_uint4)
{ /* We've waited long enough */
if (COMPSWAP_LOCK(&csa->critical->stuckexec.time_latch, next_alert_uint4, 0,
(curr_time_uint4 + MUTEXLCKALERT_INTERVAL), 0))
{ /* and no one else beat us to it */
MUTEX_DPRINT3("%d: Acquired STUCKEXEC time lock, to trace %d\n", process_id, in_crit_pid);
if (process_id == in_crit_pid)
{ /* This is just a precaution - shouldn't ever happen */
assert(FALSE);
csa->now_crit = TRUE;
return (cdb_sc_normal);
}
if (in_crit_pid && (in_crit_pid == csa->nl->in_crit) && is_proc_alive(in_crit_pid, 0))
{ /* and we're waiting on some living process */
if (local_crit_cycle == csa->critical->crit_cycle)
{ /* and things aren't moving */
assert(local_crit_cycle);
if (0 == csa->nl->onln_rlbk_pid)
{ /* not rollback - send_msg after trace less likely to lose process */
GET_C_STACK_FROM_SCRIPT("MUTEXLCKALERT", process_id, in_crit_pid,
csa->critical->crit_cycle);
send_msg(VARLSTCNT(6) ERR_MUTEXLCKALERT, 4, DB_LEN_STR(reg), in_crit_pid,
csa->critical->crit_cycle);
try_recovery = TRUE; /* set off a salvage */
continue; /* make sure to act on it soon, likely this process */
}
/* If the holding PID belongs to online rollback which holds crit on database and
* journal pool for its entire duration, use a different message
*/
send_msg(VARLSTCNT(5) ERR_ORLBKINPROG, 3, csa->nl->onln_rlbk_pid, DB_LEN_STR(reg));
assert(csa->nl->in_crit == csa->nl->onln_rlbk_pid);
}
} else
{ /* nobody home */
local_crit_cycle = csa->critical->crit_cycle;
try_recovery = TRUE; /* set off a salvage */
continue; /* make sure to act on it soon, likely this process */
}
} else
{ /* didn't get resource to do the MUTEXLCKALERT and procestuckexec */
MUTEX_DPRINT2("%d: Could not acquire STUCKEXEC time lock", process_id);
}
}
if (0 == local_crit_cycle)
local_crit_cycle = csa->critical->crit_cycle; /* sync first time waiter */
if (cdb_sc_dbccerr == mutex_sleep(csa, mutex_lock_type))
return (cdb_sc_dbccerr);
} while (TRUE);
}
/* in UNIX calls to the following two entry points should be replaced by appropriate (perhaps macro) calls to mutex_lock */
enum cdb_sc mutex_lockw(gd_region *reg, mutex_spin_parms_ptr_t mutex_spin_parms, int crash_count)
{
return (mutex_lock(reg, mutex_spin_parms, crash_count, MUTEX_LOCK_WRITE));
}
enum cdb_sc mutex_lockwim(gd_region *reg, mutex_spin_parms_ptr_t mutex_spin_parms, int crash_count)
{
return (mutex_lock(reg, mutex_spin_parms, crash_count, MUTEX_LOCK_WRITE_IMMEDIATE));
}
enum cdb_sc mutex_unlockw(gd_region *reg, int crash_count)
{
/* Unlock write access to the mutex at addr */
uint4 already_clear;
sgmnt_addrs *csa;
csa = &FILE_INFO(reg)->s_addrs;
if (crash_count != csa->critical->crashcnt)
return (cdb_sc_critreset);
assert(csa->now_crit);
MUTEX_TEST_SIGNAL_HERE("WRTUNLCK NOW CRIT\n", FALSE);
csa->now_crit = FALSE;
assert(csa->critical->semaphore.u.parts.latch_pid == process_id);
RELEASE_SWAPLOCK(&csa->critical->semaphore);
MUTEX_DPRINT2("%d: WRITE LOCK RELEASED\n", process_id);
return (mutex_wakeup(csa->critical));
}
void mutex_cleanup(gd_region *reg)
{
sgmnt_addrs *csa;
/* mutex_cleanup is called after doing a rel_crit on the same area so if we still own the lock
it is because csa->now_crit was not in sync with our semaphore. At this point, if we own
the lock, go ahead and release it.
*/
csa = &FILE_INFO(reg)->s_addrs;
if (COMPSWAP_UNLOCK(&csa->critical->semaphore, process_id, image_count, LOCK_AVAILABLE, 0))
{
MUTEX_DPRINT2("%d mutex_cleanup : released lock\n", process_id);
}
}
void mutex_seed_init(void)
{
time_t mutex_seed;
mutex_seed = time(NULL) * process_id;
next_rand[0] = (unsigned short)(mutex_seed & ((1U << (SIZEOF(unsigned short) * 8)) - 1));
mutex_seed >>= (SIZEOF(unsigned short) * 8);
next_rand[1] = (unsigned short)(mutex_seed & ((1U << (SIZEOF(unsigned short) * 8)) - 1));
mutex_seed >>= (SIZEOF(unsigned short) * 8);
next_rand[2] = (unsigned short)(mutex_seed & ((1U << (SIZEOF(unsigned short) * 8)) - 1));
}
void mutex_salvage(gd_region *reg)
{
sgmnt_addrs *csa;
int salvage_status;
pid_t holder_pid, onln_rlbk_pid;
boolean_t mutex_salvaged;
VMS_ONLY(uint4 holder_imgcnt;)
DCL_THREADGBL_ACCESS;
SETUP_THREADGBL_ACCESS;
csa = &FILE_INFO(reg)->s_addrs;
if (0 != (holder_pid = csa->critical->semaphore.u.parts.latch_pid))
{
mutex_salvaged = FALSE;
VMS_ONLY(holder_imgcnt = csa->critical->semaphore.u.parts.latch_image_count);
if (holder_pid == process_id VMS_ONLY(&& holder_imgcnt == image_count))
{ /* We were trying to obtain a lock we already held -- very odd */
RELEASE_SWAPLOCK(&csa->critical->semaphore);
csa->nl->in_crit = 0;
/* Mutex crash repaired, want to do write cache recovery, just in case.
* Take care not to do it for jnlpool which has no concept of a db cache.
* In that case csa->hdr is NULL so use CAREFUL_SET_TRACEABLE_VAR macro.
*/
CAREFUL_SET_TRACEABLE_VAR(csa, TRUE);
mutex_salvaged = TRUE;
MUTEX_DPRINT2("%d : mutex salvaged, culprit was our own process\n", process_id);
} else if (!is_proc_alive(holder_pid, UNIX_ONLY(0) VMS_ONLY(holder_imgcnt)))
{ /* Release the COMPSWAP lock AFTER setting csa->nl->in_crit to 0 as an assert in
* grab_crit (checking that csa->nl->in_crit is 0) relies on this order.
*/
send_msg(VARLSTCNT(5) ERR_MUTEXFRCDTERM, 3, holder_pid, REG_LEN_STR(reg));
csa->nl->in_crit = 0;
/* Mutex crash repaired, want to do write cache recovery, in case previous holder of crit had set
* some cr->in_cw_set to a non-zero value. Not doing cache recovery could cause incorrect
* GTMASSERTs in PIN_CACHE_RECORD macro in t_end/tp_tend.
* Take care not to do it for jnlpool which has no concept of a db cache.
* In that case csa->hdr is NULL so use CAREFUL_SET_TRACEABLE_VAR macro.
*/
CAREFUL_SET_TRACEABLE_VAR(csa, TRUE);
COMPSWAP_UNLOCK(&csa->critical->semaphore, holder_pid, holder_imgcnt, LOCK_AVAILABLE, 0);
mutex_salvaged = TRUE;
/* Reset jb->blocked as well if the holder_pid had it set */
if ((NULL != csa->jnl) && (NULL != csa->jnl->jnl_buff) && (csa->jnl->jnl_buff->blocked == holder_pid))
csa->jnl->jnl_buff->blocked = 0;
MUTEX_DPRINT3("%d : mutex salvaged, culprit was %d\n", process_id, holder_pid);
} else if (!TREF(disable_sigcont))
{
/* The process might have been STOPPED (kill -SIGSTOP). Send SIGCONT and nudge the stopped process forward.
* However, skip this call in case of SENDTO_EPERM white-box test, because we do not want the intentionally
* stuck process to be awakened prematurely. */
DEBUG_ONLY(if (!gtm_white_box_test_case_enabled || WBTEST_SENDTO_EPERM != gtm_white_box_test_case_number))
continue_proc(holder_pid);
}
/* Record salvage event in db file header if applicable.
* Take care not to do it for jnlpool which has no concept of a db cache.
* In that case csa->hdr is NULL so check accordingly.
*/
assert((NULL != csa->hdr) || (csa == &FILE_INFO(jnlpool.jnlpool_dummy_reg)->s_addrs));
if (mutex_salvaged && (NULL != csa->hdr))
{
BG_TRACE_PRO_ANY(csa, wcb_mutex_salvage); /* no need to use CAREFUL_BG_TRACE_PRO_ANY macro
* since we already checked for csa->hdr non-NULL.
*/
send_msg(VARLSTCNT(8) ERR_WCBLOCKED, 6, LEN_AND_LIT("wcb_mutex_salvage"),
process_id, &csa->ti->curr_tn, DB_LEN_STR(reg));
}
}
}
/* Do the per process initialization of mutex stuff. This function should be invoked only once per process. The only
* exception is the receiver server which could invoke this twice. Once through the receiver server startup command when
* it does "jnlpool_init" and the second through the child receiver server process initialization. The second initialization
* is needed to set the mutex structures up to correspond to the child process id (and not the parent pid). The function below
* has to be coded to ensure that the second call nullifies any effects of the first call.
*/
void mutex_per_process_init(void)
{
int4 status;
assert(process_id != mutex_per_process_init_pid);
mutex_seed_init();
# ifndef MUTEX_MSEM_WAKE
if (mutex_per_process_init_pid)
{ /* Close socket opened by the first call. But dont delete the socket file as the parent process will do that. */
assert(FD_INVALID != mutex_sock_fd);
if (FD_INVALID != mutex_sock_fd)
CLOSEFILE_RESET(mutex_sock_fd, status); /* resets "mutex_sock_fd" to FD_INVALID */
}
assert(FD_INVALID == mutex_sock_fd);
mutex_sock_init();
assert(FD_INVALID != mutex_sock_fd);
# endif
mutex_per_process_init_pid = process_id;
}
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