From 3f6a949df6ad4f20f6a53bddba1efa8cff98f2e0 Mon Sep 17 00:00:00 2001 From: fabient Date: Tue, 24 Nov 2009 19:26:53 +0000 Subject: - fix a LOR between process lock and pmc thread mutex - fix a system deadlock on process exit when the sample buffer is full (pmclog_loop blocked in fo_write) and pmcstat exit. Reviewed by: jkoshy MFC after: 3 weeks --- sys/dev/hwpmc/hwpmc_logging.c | 33 +++++++++++++++++++-------------- 1 file changed, 19 insertions(+), 14 deletions(-) (limited to 'sys/dev/hwpmc/hwpmc_logging.c') diff --git a/sys/dev/hwpmc/hwpmc_logging.c b/sys/dev/hwpmc/hwpmc_logging.c index cfb055b..a36a8dc 100644 --- a/sys/dev/hwpmc/hwpmc_logging.c +++ b/sys/dev/hwpmc/hwpmc_logging.c @@ -240,6 +240,7 @@ pmclog_loop(void *arg) int error; struct pmc_owner *po; struct pmclog_buffer *lb; + struct proc *p; struct ucred *ownercred; struct ucred *mycred; struct thread *td; @@ -248,12 +249,13 @@ pmclog_loop(void *arg) size_t nbytes; po = (struct pmc_owner *) arg; + p = po->po_owner; td = curthread; mycred = td->td_ucred; - PROC_LOCK(po->po_owner); - ownercred = crhold(po->po_owner->p_ucred); - PROC_UNLOCK(po->po_owner); + PROC_LOCK(p); + ownercred = crhold(p->p_ucred); + PROC_UNLOCK(p); PMCDBG(LOG,INI,1, "po=%p kt=%p", po, po->po_kthread); KASSERT(po->po_kthread == curthread->td_proc, @@ -324,16 +326,16 @@ pmclog_loop(void *arg) error = fo_write(po->po_file, &auio, ownercred, 0, td); td->td_ucred = mycred; - mtx_lock(&pmc_kthread_mtx); - if (error) { /* XXX some errors are recoverable */ /* XXX also check for SIGPIPE if a socket */ /* send a SIGIO to the owner and exit */ - PROC_LOCK(po->po_owner); - psignal(po->po_owner, SIGIO); - PROC_UNLOCK(po->po_owner); + PROC_LOCK(p); + psignal(p, SIGIO); + PROC_UNLOCK(p); + + mtx_lock(&pmc_kthread_mtx); po->po_error = error; /* save for flush log */ @@ -342,6 +344,8 @@ pmclog_loop(void *arg) break; } + mtx_lock(&pmc_kthread_mtx); + /* put the used buffer back into the global pool */ PMCLOG_INIT_BUFFER_DESCRIPTOR(lb); @@ -525,15 +529,20 @@ static void pmclog_stop_kthread(struct pmc_owner *po) { /* - * Unset flag, wakeup the helper thread, + * Close the file to force the thread out of fo_write, + * unset flag, wakeup the helper thread, * wait for it to exit */ - mtx_assert(&pmc_kthread_mtx, MA_OWNED); + if (po->po_file != NULL) + fo_close(po->po_file, curthread); + + mtx_lock(&pmc_kthread_mtx); po->po_flags &= ~PMC_PO_OWNS_LOGFILE; wakeup_one(po); if (po->po_kthread) msleep(po->po_kthread, &pmc_kthread_mtx, PPAUSE, "pmckstp", 0); + mtx_unlock(&pmc_kthread_mtx); } /* @@ -602,10 +611,8 @@ pmclog_configure_log(struct pmc_mdep *md, struct pmc_owner *po, int logfd) error: /* shutdown the thread */ - mtx_lock(&pmc_kthread_mtx); if (po->po_kthread) pmclog_stop_kthread(po); - mtx_unlock(&pmc_kthread_mtx); KASSERT(po->po_kthread == NULL, ("[pmclog,%d] po=%p kthread not " "stopped", __LINE__, po)); @@ -641,10 +648,8 @@ pmclog_deconfigure_log(struct pmc_owner *po) ("[pmclog,%d] po=%p no log file", __LINE__, po)); /* stop the kthread, this will reset the 'OWNS_LOGFILE' flag */ - mtx_lock(&pmc_kthread_mtx); if (po->po_kthread) pmclog_stop_kthread(po); - mtx_unlock(&pmc_kthread_mtx); KASSERT(po->po_kthread == NULL, ("[pmclog,%d] po=%p kthread not stopped", __LINE__, po)); -- cgit v1.1