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authorNicholas Bellinger <nab@linux-iscsi.org>2014-01-28 17:56:30 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-02-13 13:55:41 -0800
commit96330e5ec172d304d84f214d551ed3e9f520188a (patch)
treee2780918b3a7319c3ae16b50290de2437ee37081 /include
parent6cb630d2d77349364f446d1db908d08f1877c768 (diff)
target: Fix percpu_ref_put race in transport_lun_remove_cmd
commit 5259a06ef97068b710f45d092a587e8d740f750f upstream. This patch fixes a percpu_ref_put race for se_lun->lun_ref in transport_lun_remove_cmd() where ->lun_ref could end up being put more than once per command via different target completion and fabric release contexts. It adds a cmpxchg() for se_cmd->lun_ref_active to ensure that percpu_ref_put() is only ever called once per se_cmd. This bug was manifesting itself as a LUN shutdown regression bug in >= v3.13 code, where percpu_ref_kill() would end up hanging indefinately due to the incorrect percpu_ref count. (Change se_cmd->lun_ref_active from bool -> int to force at least a 4-byte cmpxchg with MIPS ll/sc ins. - Fengguang) Reported-by: Tommy Apel <tommyapeldk@gmail.com> Cc: Tommy Apel <tommyapeldk@gmail.com> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/target/target_core_base.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index 321301c0a643..e3569f829f7e 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -497,7 +497,7 @@ struct se_cmd {
void *priv;
/* Used for lun->lun_ref counting */
- bool lun_ref_active;
+ int lun_ref_active;
};
struct se_ua {