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Date:      Fri, 11 Mar 2016 11:51:38 +0000 (UTC)
From:      Konstantin Belousov <kib@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r296652 - head/sys/fs/pseudofs
Message-ID:  <201603111151.u2BBpc7m092213@repo.freebsd.org>
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Author: kib
Date: Fri Mar 11 11:51:38 2016
New Revision: 296652
URL: https://svnweb.freebsd.org/changeset/base/296652

Log:
  Do not perform unneccessary shared recursion on the allproc_lock in
  pfs_visible().  The recursion does not cause deadlock because the sx
  implementation does not prefer exclusive waiters over the shared, but
  this is an implementation detail.
  
  Reported by:	pho, Matthew Bryan <matthew.bryan@isilon.com>
  Reviewed by:	jhb
  Tested by:	pho
  Approved by:	des (pseudofs maintainer)
  Sponsored by:	The FreeBSD Foundation
  MFC after:	2 weeks

Modified:
  head/sys/fs/pseudofs/pseudofs_vnops.c

Modified: head/sys/fs/pseudofs/pseudofs_vnops.c
==============================================================================
--- head/sys/fs/pseudofs/pseudofs_vnops.c	Fri Mar 11 11:38:31 2016	(r296651)
+++ head/sys/fs/pseudofs/pseudofs_vnops.c	Fri Mar 11 11:51:38 2016	(r296652)
@@ -104,7 +104,8 @@ pfs_visible_proc(struct thread *td, stru
 }
 
 static int
-pfs_visible(struct thread *td, struct pfs_node *pn, pid_t pid, struct proc **p)
+pfs_visible(struct thread *td, struct pfs_node *pn, pid_t pid,
+    bool allproc_locked, struct proc **p)
 {
 	struct proc *proc;
 
@@ -115,7 +116,8 @@ pfs_visible(struct thread *td, struct pf
 		*p = NULL;
 	if (pid == NO_PID)
 		PFS_RETURN (1);
-	if ((proc = pfind(pid)) == NULL)
+	proc = allproc_locked ? pfind_locked(pid) : pfind(pid);
+	if (proc == NULL)
 		PFS_RETURN (0);
 	if (pfs_visible_proc(td, pn, proc)) {
 		if (p)
@@ -202,7 +204,7 @@ pfs_getattr(struct vop_getattr_args *va)
 	PFS_TRACE(("%s", pn->pn_name));
 	pfs_assert_not_owned(pn);
 
-	if (!pfs_visible(curthread, pn, pvd->pvd_pid, &proc))
+	if (!pfs_visible(curthread, pn, pvd->pvd_pid, false, &proc))
 		PFS_RETURN (ENOENT);
 
 	vap->va_type = vn->v_type;
@@ -293,7 +295,7 @@ pfs_ioctl(struct vop_ioctl_args *va)
 	 * This is necessary because process' privileges may
 	 * have changed since the open() call.
 	 */
-	if (!pfs_visible(curthread, pn, pvd->pvd_pid, &proc)) {
+	if (!pfs_visible(curthread, pn, pvd->pvd_pid, false, &proc)) {
 		VOP_UNLOCK(vn, 0);
 		PFS_RETURN (EIO);
 	}
@@ -326,7 +328,7 @@ pfs_getextattr(struct vop_getextattr_arg
 	 * This is necessary because either process' privileges may
 	 * have changed since the open() call.
 	 */
-	if (!pfs_visible(curthread, pn, pvd->pvd_pid, &proc))
+	if (!pfs_visible(curthread, pn, pvd->pvd_pid, false, &proc))
 		PFS_RETURN (EIO);
 
 	if (pn->pn_getextattr == NULL)
@@ -462,7 +464,7 @@ pfs_lookup(struct vop_cachedlookup_args 
 		PFS_RETURN (ENOENT);
 
 	/* check that parent directory is visible... */
-	if (!pfs_visible(curthread, pd, pvd->pvd_pid, NULL))
+	if (!pfs_visible(curthread, pd, pvd->pvd_pid, false, NULL))
 		PFS_RETURN (ENOENT);
 
 	/* self */
@@ -546,7 +548,7 @@ pfs_lookup(struct vop_cachedlookup_args 
  got_pnode:
 	pfs_assert_not_owned(pd);
 	pfs_assert_not_owned(pn);
-	visible = pfs_visible(curthread, pn, pid, NULL);
+	visible = pfs_visible(curthread, pn, pid, false, NULL);
 	if (!visible) {
 		error = ENOENT;
 		goto failed;
@@ -635,7 +637,7 @@ pfs_read(struct vop_read_args *va)
 	 * This is necessary because either process' privileges may
 	 * have changed since the open() call.
 	 */
-	if (!pfs_visible(curthread, pn, pvd->pvd_pid, &proc))
+	if (!pfs_visible(curthread, pn, pvd->pvd_pid, false, &proc))
 		PFS_RETURN (EIO);
 	if (proc != NULL) {
 		_PHOLD(proc);
@@ -791,7 +793,7 @@ pfs_readdir(struct vop_readdir_args *va)
 	pfs_lock(pd);
 
         /* check if the directory is visible to the caller */
-        if (!pfs_visible(curthread, pd, pid, &proc)) {
+        if (!pfs_visible(curthread, pd, pid, true, &proc)) {
 		sx_sunlock(&allproc_lock);
 		pfs_unlock(pd);
                 PFS_RETURN (ENOENT);
@@ -995,7 +997,7 @@ pfs_write(struct vop_write_args *va)
 	 * This is necessary because either process' privileges may
 	 * have changed since the open() call.
 	 */
-	if (!pfs_visible(curthread, pn, pvd->pvd_pid, &proc))
+	if (!pfs_visible(curthread, pn, pvd->pvd_pid, false, &proc))
 		PFS_RETURN (EIO);
 	if (proc != NULL) {
 		_PHOLD(proc);

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