mirror of https://github.com/torvalds/linux.git
5259a06ef9
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> Cc: <stable@vger.kernel.org> #3.13+ Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org> |
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