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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:
markj 2017-11-23 14:29:07 +00:00
parent 36a1a14004
commit b7a8474133
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);