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Duplicate helpers after disabling inherited tracepoints during a fork.

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We may create probes in the nascent child process, so we first need to
ensure that any inherited tracepoints are first removed. Otherwise the
probe sites will not be in the state expected by fasttrap, and it won't
be able to enable the probes.

MFC after:	2 weeks
This commit is contained in:
Mark Johnston 2017-11-23 14:29:07 +00:00
parent 0349817103
commit e9f63df76d
1 changed files with 8 additions and 14 deletions
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22
sys/cddl/contrib/opensolaris/uts/common/dtrace/fasttrap.c
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@ -601,8 +601,8 @@ fasttrap_fork(proc_t *p, proc_t *cp)
pid_t ppid = p->p_pid;
int i;
#ifdef illumos
ASSERT(curproc == p);
#ifdef illumos
ASSERT(p->p_proc_flag & P_PR_LOCK);
#else
PROC_LOCK_ASSERT(p, MA_OWNED);
@ -610,26 +610,15 @@ fasttrap_fork(proc_t *p, proc_t *cp)
#ifdef illumos
ASSERT(p->p_dtrace_count > 0);
#else
if (p->p_dtrace_helpers) {
/*
* dtrace_helpers_duplicate() allocates memory.
*/
_PHOLD(cp);
PROC_UNLOCK(p);
PROC_UNLOCK(cp);
dtrace_helpers_duplicate(p, cp);
PROC_LOCK(cp);
PROC_LOCK(p);
_PRELE(cp);
}
/*
* This check is purposely here instead of in kern_fork.c because,
* for legal resons, we cannot include the dtrace_cddl.h header
* inside kern_fork.c and insert if-clause there.
*/
if (p->p_dtrace_count == 0)
if (p->p_dtrace_count == 0 && p->p_dtrace_helpers == NULL)
return;
#endif
ASSERT(cp->p_dtrace_count == 0);
/*
@ -658,6 +647,8 @@ fasttrap_fork(proc_t *p, proc_t *cp)
_PHOLD(cp);
PROC_UNLOCK(cp);
PROC_UNLOCK(p);
if (p->p_dtrace_count == 0)
goto dup_helpers;
#endif
/*
@ -711,6 +702,9 @@ fasttrap_fork(proc_t *p, proc_t *cp)
mutex_enter(&cp->p_lock);
sprunlock(cp);
#else
dup_helpers:
if (p->p_dtrace_helpers != NULL)
dtrace_helpers_duplicate(p, cp);
PROC_LOCK(p);
PROC_LOCK(cp);
_PRELE(cp);