Author: kib
Date: Sun Jul 28 06:59:29 2013
New Revision: 253737
URL: http://svnweb.freebsd.org/changeset/base/253737
Log:
When creation of the v_pollinfo raced and our instance of vpollinfo
must be destroyed, knlist_clear() and seldrain() calls could be
avoided, since vpollinfo was not used. More, the knlist_clear()
calling protocol requires the knlist locked, which is not true at the
call site.
Split the destruction into the helper destroy_vpollinfo_free(), and
call it when raced, instead of destroy_vpollinfo().
Reported and tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 3 days
Modified:
head/sys/kern/vfs_subr.c
Modified: head/sys/kern/vfs_subr.c
==============================================================================
--- head/sys/kern/vfs_subr.c Sun Jul 28 06:16:12 2013 (r253736)
+++ head/sys/kern/vfs_subr.c Sun Jul 28 06:59:29 2013 (r253737)
@@ -3453,16 +3453,23 @@ vfs_msync(struct mount *mp, int flags)
}
static void
-destroy_vpollinfo(struct vpollinfo *vi)
+destroy_vpollinfo_free(struct vpollinfo *vi)
{
- knlist_clear(&vi->vpi_selinfo.si_note, 1);
- seldrain(&vi->vpi_selinfo);
knlist_destroy(&vi->vpi_selinfo.si_note);
mtx_destroy(&vi->vpi_lock);
uma_zfree(vnodepoll_zone, vi);
}
+static void
+destroy_vpollinfo(struct vpollinfo *vi)
+{
+
+ knlist_clear(&vi->vpi_selinfo.si_note, 1);
+ seldrain(&vi->vpi_selinfo);
+ destroy_vpollinfo_free(vi);
+}
+
/*
* Initalize per-vnode helper structure to hold poll-related state.
*/
@@ -3480,7 +3487,7 @@ v_addpollinfo(struct vnode *vp)
VI_LOCK(vp);
if (vp->v_pollinfo != NULL) {
VI_UNLOCK(vp);
- destroy_vpollinfo(vi);
+ destroy_vpollinfo_free(vi);
return;
}
vp->v_pollinfo = vi;
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