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authorGabriel Krisman Bertazi <krisman@linux.vnet.ibm.com>2016-07-29 22:15:18 +0300
committerJens Axboe <axboe@fb.com>2016-08-15 18:46:46 +0300
commitf6b6a28e2dbc401416ff12f775d75281c9b41918 (patch)
tree88f3765ae063a57ee5b1180af0839f5c7be36c39 /drivers/nvme
parent694d0d0bb2030d2e36df73e2d23d5770511dbc8d (diff)
downloadlinux-f6b6a28e2dbc401416ff12f775d75281c9b41918.tar.xz
nvme: Prevent controller state invalid transition
Acquiring the nvme_ctrl lock before reading ctrl->state in nvme_change_ctrl_state() should prevent a theoretical invalid state transition, in the event of two threads racing inside that function. I haven't been able to observe this happening with the current code, and the current state machine seems to be simple enough to not be affected by these invalid transitions, but future modifications could make it more likely to happen. Signed-off-by: Gabriel Krisman Bertazi <krisman@linux.vnet.ibm.com> Reviewed-by: Sagi Grimberg <sag@grimberg.me> Reviewed-by: Steve Wise <swise@opengridcomputing.com> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'drivers/nvme')
-rw-r--r--drivers/nvme/host/core.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 7ff2e820bbf4..7f75d661237f 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -81,10 +81,12 @@ EXPORT_SYMBOL_GPL(nvme_cancel_request);
bool nvme_change_ctrl_state(struct nvme_ctrl *ctrl,
enum nvme_ctrl_state new_state)
{
- enum nvme_ctrl_state old_state = ctrl->state;
+ enum nvme_ctrl_state old_state;
bool changed = false;
spin_lock_irq(&ctrl->lock);
+
+ old_state = ctrl->state;
switch (new_state) {
case NVME_CTRL_LIVE:
switch (old_state) {
@@ -140,11 +142,12 @@ bool nvme_change_ctrl_state(struct nvme_ctrl *ctrl,
default:
break;
}
- spin_unlock_irq(&ctrl->lock);
if (changed)
ctrl->state = new_state;
+ spin_unlock_irq(&ctrl->lock);
+
return changed;
}
EXPORT_SYMBOL_GPL(nvme_change_ctrl_state);