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Do not perform unneccessary shared recursion on the allproc_lock in

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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
This commit is contained in:
Konstantin Belousov 2016-03-11 11:51:38 +00:00
parent e7c246c5f1
commit ffc161df9f
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=296652
1 changed files with 12 additions and 10 deletions
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22
sys/fs/pseudofs/pseudofs_vnops.c
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@ -104,7 +104,8 @@ pfs_visible_proc(struct thread *td, struct pfs_node *pn, struct proc *proc)
}
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 pfs_node *pn, pid_t pid, struct proc **p)
*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_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 (pn->pn_getextattr == NULL)
@ -462,7 +464,7 @@ pfs_lookup(struct vop_cachedlookup_args *va)
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 *va)
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);