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Cleanup: spa vdev processing should check NULL pointers 

The PVS Studio 2016 FreeBSD kernel report stated:

\contrib\opensolaris\uts\common\fs\zfs\spa.c (1341): error V595: The 'spa->spa_spares.sav_vdevs' pointer was utilized before it was verified against nullptr. Check lines: 1341, 1342.
\sys\cddl\contrib\opensolaris\uts\common\fs\zfs\spa.c (1355): error V595: The 'spa->spa_l2cache.sav_vdevs' pointer was utilized before it was verified against nullptr. Check lines: 1355, 1357.
\sys\cddl\contrib\opensolaris\uts\common\fs\zfs\spa.c (1398): error V595: The 'spa->spa_spares.sav_vdevs' pointer was utilized before it was verified against nullptr. Check lines: 1398, 1408.
\sys\cddl\contrib\opensolaris\uts\common\fs\zfs\spa.c (1583): error V595: The 'oldvdevs' pointer was utilized before it was verified against nullptr. Check lines: 1583, 1595.

In practice, all of these uses were safe because a NULL pointer
implied a 0 vdev count, which kept us from iterating over vdevs.
However, rearranging the code to check the pointer first is not a
terrible micro-optimization and makes it more readable, so let us
do that.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Brian Atkinson <batkinson@lanl.gov>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes #14456
This commit is contained in:
Richard Yao 2023-01-23 15:03:21 -05:00 committed by Brian Behlendorf
parent 3a7d2a0ce0
commit cfb49616cd
1 changed files with 30 additions and 28 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

58
module/zfs/spa.c
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@ -1714,9 +1714,9 @@ spa_unload(spa_t *spa)
*/ */
spa_l2cache_drop(spa); spa_l2cache_drop(spa);
for (int i = 0; i < spa->spa_spares.sav_count; i++)
vdev_free(spa->spa_spares.sav_vdevs[i]);
if (spa->spa_spares.sav_vdevs) { if (spa->spa_spares.sav_vdevs) {
for (int i = 0; i < spa->spa_spares.sav_count; i++)
vdev_free(spa->spa_spares.sav_vdevs[i]);
kmem_free(spa->spa_spares.sav_vdevs, kmem_free(spa->spa_spares.sav_vdevs,
spa->spa_spares.sav_count * sizeof (void *)); spa->spa_spares.sav_count * sizeof (void *));
spa->spa_spares.sav_vdevs = NULL; spa->spa_spares.sav_vdevs = NULL;
@ -1727,11 +1727,11 @@ spa_unload(spa_t *spa)
} }
spa->spa_spares.sav_count = 0; spa->spa_spares.sav_count = 0;
for (int i = 0; i < spa->spa_l2cache.sav_count; i++) {
vdev_clear_stats(spa->spa_l2cache.sav_vdevs[i]);
vdev_free(spa->spa_l2cache.sav_vdevs[i]);
}
if (spa->spa_l2cache.sav_vdevs) { if (spa->spa_l2cache.sav_vdevs) {
for (int i = 0; i < spa->spa_l2cache.sav_count; i++) {
vdev_clear_stats(spa->spa_l2cache.sav_vdevs[i]);
vdev_free(spa->spa_l2cache.sav_vdevs[i]);
}
kmem_free(spa->spa_l2cache.sav_vdevs, kmem_free(spa->spa_l2cache.sav_vdevs,
spa->spa_l2cache.sav_count * sizeof (void *)); spa->spa_l2cache.sav_count * sizeof (void *));
spa->spa_l2cache.sav_vdevs = NULL; spa->spa_l2cache.sav_vdevs = NULL;
@ -1789,20 +1789,21 @@ spa_load_spares(spa_t *spa)
/* /*
* First, close and free any existing spare vdevs. * First, close and free any existing spare vdevs.
*/ */
for (i = 0; i < spa->spa_spares.sav_count; i++) { if (spa->spa_spares.sav_vdevs) {
vd = spa->spa_spares.sav_vdevs[i]; for (i = 0; i < spa->spa_spares.sav_count; i++) {
vd = spa->spa_spares.sav_vdevs[i];
/* Undo the call to spa_activate() below */ /* Undo the call to spa_activate() below */
if ((tvd = spa_lookup_by_guid(spa, vd->vdev_guid, if ((tvd = spa_lookup_by_guid(spa, vd->vdev_guid,
B_FALSE)) != NULL && tvd->vdev_isspare) B_FALSE)) != NULL && tvd->vdev_isspare)
spa_spare_remove(tvd); spa_spare_remove(tvd);
vdev_close(vd); vdev_close(vd);
vdev_free(vd); vdev_free(vd);
} }
if (spa->spa_spares.sav_vdevs)
kmem_free(spa->spa_spares.sav_vdevs, kmem_free(spa->spa_spares.sav_vdevs,
spa->spa_spares.sav_count * sizeof (void *)); spa->spa_spares.sav_count * sizeof (void *));
}
if (spa->spa_spares.sav_config == NULL) if (spa->spa_spares.sav_config == NULL)
nspares = 0; nspares = 0;
@ -2013,23 +2014,24 @@ out:
/* /*
* Purge vdevs that were dropped * Purge vdevs that were dropped
*/ */
for (i = 0; i < oldnvdevs; i++) { if (oldvdevs) {
uint64_t pool; for (i = 0; i < oldnvdevs; i++) {
uint64_t pool;
vd = oldvdevs[i]; vd = oldvdevs[i];
if (vd != NULL) { if (vd != NULL) {
ASSERT(vd->vdev_isl2cache); ASSERT(vd->vdev_isl2cache);
if (spa_l2cache_exists(vd->vdev_guid, &pool) && if (spa_l2cache_exists(vd->vdev_guid, &pool) &&
pool != 0ULL && l2arc_vdev_present(vd)) pool != 0ULL && l2arc_vdev_present(vd))
l2arc_remove_vdev(vd); l2arc_remove_vdev(vd);
vdev_clear_stats(vd); vdev_clear_stats(vd);
vdev_free(vd); vdev_free(vd);
}
} }
}
if (oldvdevs)
kmem_free(oldvdevs, oldnvdevs * sizeof (void *)); kmem_free(oldvdevs, oldnvdevs * sizeof (void *));
}
for (i = 0; i < sav->sav_count; i++) for (i = 0; i < sav->sav_count; i++)
nvlist_free(l2cache[i]); nvlist_free(l2cache[i]);