Commit a64e7a79 authored by Brian Norris's avatar Brian Norris Committed by Kalle Valo

mwifiex: resolve reset vs. remove()/shutdown() deadlocks

Commit b014e96d ("PCI: Protect pci_error_handlers->reset_notify()
usage with device_lock()") resolves races between driver reset and
removal, but it introduces some new deadlock problems. If we see a
timeout while we've already started suspending, removing, or shutting
down the driver, we might see:

(a) a worker thread, running mwifiex_pcie_work() ->
    mwifiex_pcie_card_reset_work() -> pci_reset_function()
(b) a removal thread, running mwifiex_pcie_remove() ->
    mwifiex_free_adapter() -> mwifiex_unregister() ->
    mwifiex_cleanup_pcie() -> cancel_work_sync(&card->work)

Unfortunately, mwifiex_pcie_remove() already holds the device lock that
pci_reset_function() is now requesting, and so we see a deadlock.

It's necessary to cancel and synchronize our outstanding work before
tearing down the driver, so we can't have this work wait indefinitely
for the lock.

It's reasonable to only "try" to reset here, since this will mostly
happen for cases where it's already difficult to reset the firmware
anyway (e.g., while we're suspending or powering off the system). And if
reset *really* needs to happen, we can always try again later.

Fixes: b014e96d ("PCI: Protect pci_error_handlers->reset_notify() usage with device_lock()")
Cc: <stable@vger.kernel.org>
Cc: Xinming Hu <huxm@marvell.com>
Signed-off-by: default avatarBrian Norris <briannorris@chromium.org>
Signed-off-by: default avatarKalle Valo <kvalo@codeaurora.org>
parent 7e34c0d2
...@@ -2786,7 +2786,10 @@ static void mwifiex_pcie_card_reset_work(struct mwifiex_adapter *adapter) ...@@ -2786,7 +2786,10 @@ static void mwifiex_pcie_card_reset_work(struct mwifiex_adapter *adapter)
{ {
struct pcie_service_card *card = adapter->card; struct pcie_service_card *card = adapter->card;
pci_reset_function(card->dev); /* We can't afford to wait here; remove() might be waiting on us. If we
* can't grab the device lock, maybe we'll get another chance later.
*/
pci_try_reset_function(card->dev);
} }
static void mwifiex_pcie_work(struct work_struct *work) static void mwifiex_pcie_work(struct work_struct *work)
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment