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bdev: hold spinlock while changing claim_module

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This closes races between concurrent spdk_bdev_module_claim_bdev()
and/or spdk_bdev_module_release_bdev() calls affecting the same bdev by
holding bdev->internal.spinlock while claiming and releasing a bdev. It
also closes a potential TOCTOU bug in that optimizing compilers probably
already eliminate in bdev_finish_unregister_bdevs_iter() and documents
that bdev->internal.claim_module is protected by
bdev->internal.spinlock.

This can be removed when the bdev_register_examine_thread deprecation
is removed.

Signed-off-by: Mike Gerdts <mgerdts@nvidia.com>
Change-Id: Ib48552df065d5172139a61bbc00b391f36552c0c
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/15282
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Shuhei Matsumoto <smatsumoto@nvidia.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Community-CI: Mellanox Build Bot
This commit is contained in:
Mike Gerdts 2022-10-26 23:13:59 -05:00 committed by Jim Harris
parent b5075dcc5b
commit 7241a075be
2 changed files with 14 additions and 1 deletions
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3
include/spdk/bdev_module.h
View File

@ -524,7 +524,8 @@ struct spdk_bdev {
/**
* Pointer to the module that has claimed this bdev for purposes of creating virtual
* bdevs on top of it. Set to NULL if the bdev has not been claimed.
* bdevs on top of it. Set to NULL if the bdev has not been claimed. Must hold
* spinlock on all updates.
*/
struct spdk_bdev_module *claim_module;

12
lib/bdev/bdev.c
View File

@ -1818,11 +1818,14 @@ bdev_finish_unregister_bdevs_iter(void *cb_arg, int bdeverrno)
*/
for (bdev = TAILQ_LAST(&g_bdev_mgr.bdevs, spdk_bdev_list);
bdev; bdev = TAILQ_PREV(bdev, spdk_bdev_list, internal.link)) {
spdk_spin_lock(&bdev->internal.spinlock);
if (bdev->internal.claim_module != NULL) {
SPDK_DEBUGLOG(bdev, "Skipping claimed bdev '%s'(<-'%s').\n",
bdev->name, bdev->internal.claim_module->name);
spdk_spin_unlock(&bdev->internal.spinlock);
continue;
}
spdk_spin_unlock(&bdev->internal.spinlock);
SPDK_DEBUGLOG(bdev, "Unregistering bdev '%s'\n", bdev->name);
spdk_bdev_unregister(bdev, bdev_finish_unregister_bdevs_iter, bdev);
@ -7276,9 +7279,12 @@ int
spdk_bdev_module_claim_bdev(struct spdk_bdev *bdev, struct spdk_bdev_desc *desc,
struct spdk_bdev_module *module)
{
spdk_spin_lock(&bdev->internal.spinlock);
if (bdev->internal.claim_module != NULL) {
SPDK_ERRLOG("bdev %s already claimed by module %s\n", bdev->name,
bdev->internal.claim_module->name);
spdk_spin_unlock(&bdev->internal.spinlock);
return -EPERM;
}
@ -7287,14 +7293,20 @@ spdk_bdev_module_claim_bdev(struct spdk_bdev *bdev, struct spdk_bdev_desc *desc,
}
bdev->internal.claim_module = module;
spdk_spin_unlock(&bdev->internal.spinlock);
return 0;
}
void
spdk_bdev_module_release_bdev(struct spdk_bdev *bdev)
{
spdk_spin_lock(&bdev->internal.spinlock);
assert(bdev->internal.claim_module != NULL);
bdev->internal.claim_module = NULL;
spdk_spin_unlock(&bdev->internal.spinlock);
}
struct spdk_bdev *