Author: mjg
Date: Fri May 27 15:03:38 2016
New Revision: 300851
URL: https://svnweb.freebsd.org/changeset/base/300851
Log:
exec: get rid of one vnode lock/unlock pair in do_execve
The lock was temporarily dropped for vrele calls, but they can be
postponed to a point where the lock is not held in the first place.
While here shuffle other code not needing the lock.
Modified:
head/sys/kern/kern_exec.c
Modified: head/sys/kern/kern_exec.c
==============================================================================
--- head/sys/kern/kern_exec.c Fri May 27 12:02:12 2016 (r300850)
+++ head/sys/kern/kern_exec.c Fri May 27 15:03:38 2016 (r300851)
@@ -364,7 +364,7 @@ do_execve(td, args, mac_p)
struct vattr attr;
int (*img_first)(struct image_params *);
struct pargs *oldargs = NULL, *newargs = NULL;
- struct sigacts *oldsigacts, *newsigacts;
+ struct sigacts *oldsigacts = NULL, *newsigacts = NULL;
#ifdef KTRACE
struct vnode *tracevp = NULL;
struct ucred *tracecred = NULL;
@@ -714,8 +714,6 @@ interpret:
bcopy(imgp->args->begin_argv, newargs->ar_args, i);
}
- vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
-
/*
* For security and other reasons, signal handlers cannot
* be shared after an exec. The new process gets a copy of the old
@@ -726,11 +724,10 @@ interpret:
oldsigacts = p->p_sigacts;
newsigacts = sigacts_alloc();
sigacts_copy(newsigacts, oldsigacts);
- } else {
- oldsigacts = NULL;
- newsigacts = NULL; /* satisfy gcc */
}
+ vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
+
PROC_LOCK(p);
if (oldsigacts)
p->p_sigacts = newsigacts;
@@ -791,9 +788,9 @@ interpret:
VOP_UNLOCK(imgp->vp, 0);
fdsetugidsafety(td);
error = fdcheckstd(td);
- if (error != 0)
- goto done1;
vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
+ if (error != 0)
+ goto exec_fail_dealloc;
PROC_LOCK(p);
#ifdef MAC
if (will_transition) {
@@ -881,32 +878,7 @@ interpret:
SDT_PROBE1(proc, , , exec__success, args->fname);
- VOP_UNLOCK(imgp->vp, 0);
-done1:
- /*
- * Handle deferred decrement of ref counts.
- */
- if (oldtextvp != NULL)
- vrele(oldtextvp);
-#ifdef KTRACE
- if (tracevp != NULL)
- vrele(tracevp);
- if (tracecred != NULL)
- crfree(tracecred);
-#endif
- vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
- pargs_drop(oldargs);
- pargs_drop(newargs);
- if (oldsigacts != NULL)
- sigacts_free(oldsigacts);
-
exec_fail_dealloc:
- /*
- * free various allocated resources
- */
- if (euip != NULL)
- uifree(euip);
-
if (imgp->firstpage != NULL)
exec_unmap_first_page(imgp);
@@ -936,18 +908,16 @@ exec_fail_dealloc:
* the S_EXEC bit set.
*/
STOPEVENT(p, S_EXEC, 0);
- goto done2;
- }
-
+ } else {
exec_fail:
- /* we're done here, clear P_INEXEC */
- PROC_LOCK(p);
- p->p_flag &= ~P_INEXEC;
- PROC_UNLOCK(p);
+ /* we're done here, clear P_INEXEC */
+ PROC_LOCK(p);
+ p->p_flag &= ~P_INEXEC;
+ PROC_UNLOCK(p);
- SDT_PROBE1(proc, , , exec__failure, error);
+ SDT_PROBE1(proc, , , exec__failure, error);
+ }
-done2:
if (imgp->newcred != NULL)
crfree(oldcred);
#ifdef MAC
@@ -956,6 +926,24 @@ done2:
#endif
exec_free_args(args);
+ /*
+ * Handle deferred decrement of ref counts.
+ */
+ if (oldtextvp != NULL)
+ vrele(oldtextvp);
+#ifdef KTRACE
+ if (tracevp != NULL)
+ vrele(tracevp);
+ if (tracecred != NULL)
+ crfree(tracecred);
+#endif
+ pargs_drop(oldargs);
+ pargs_drop(newargs);
+ if (oldsigacts != NULL)
+ sigacts_free(oldsigacts);
+ if (euip != NULL)
+ uifree(euip);
+
if (error && imgp->vmspace_destroyed) {
/* sorry, no more process anymore. exit gracefully */
exit1(td, 0, SIGABRT);
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