[PATCH v2] ath10k: skip ath10k_halt during suspend for driver state RESTARTING

[Abhishek Kumar <kuabhs@chromium.org>]

Double free crash is observed when FW recovery(caused by wmi
timeout/crash) is followed by immediate suspend event. The FW recovery
is triggered by ath10k_core_restart() which calls driver clean up via
ath10k_halt(). When the suspend event occurs between the FW recovery,
the restart worker thread is put into frozen state until suspend completes.
The suspend event triggers ath10k_stop() which again triggers ath10k_halt()
The double invocation of ath10k_halt() causes ath10k_htt_rx_free() to be
called twice(Note: ath10k_htt_rx_alloc was not called by restart worker
thread because of its frozen state), causing the crash.

To fix this, during the suspend flow, skip call to ath10k_halt() in
ath10k_stop() when the current driver state is ATH10K_STATE_RESTARTING.
Also, for driver state ATH10K_STATE_RESTARTING, call
ath10k_wait_for_suspend() in ath10k_stop(). This is because call to
ath10k_wait_for_suspend() is skipped later in
[ath10k_halt() > ath10k_core_stop()] for the driver state
ATH10K_STATE_RESTARTING.

The frozen restart worker thread will be cancelled during resume when the
device comes out of suspend.

Below is the crash stack for reference:

[  428.469167] ------------[ cut here ]------------
[  428.469180] kernel BUG at mm/slub.c:4150!
[  428.469193] invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
[  428.469219] Workqueue: events_unbound async_run_entry_fn
[  428.469230] RIP: 0010:kfree+0x319/0x31b
[  428.469241] RSP: 0018:ffffa1fac015fc30 EFLAGS: 00010246
[  428.469247] RAX: ffffedb10419d108 RBX: ffff8c05262b0000
[  428.469252] RDX: ffff8c04a8c07000 RSI: 0000000000000000
[  428.469256] RBP: ffffa1fac015fc78 R08: 0000000000000000
[  428.469276] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  428.469285] Call Trace:
[  428.469295]  ? dma_free_attrs+0x5f/0x7d
[  428.469320]  ath10k_core_stop+0x5b/0x6f
[  428.469336]  ath10k_halt+0x126/0x177
[  428.469352]  ath10k_stop+0x41/0x7e
[  428.469387]  drv_stop+0x88/0x10e
[  428.469410]  __ieee80211_suspend+0x297/0x411
[  428.469441]  rdev_suspend+0x6e/0xd0
[  428.469462]  wiphy_suspend+0xb1/0x105
[  428.469483]  ? name_show+0x2d/0x2d
[  428.469490]  dpm_run_callback+0x8c/0x126
[  428.469511]  ? name_show+0x2d/0x2d
[  428.469517]  __device_suspend+0x2e7/0x41b
[  428.469523]  async_suspend+0x1f/0x93
[  428.469529]  async_run_entry_fn+0x3d/0xd1
[  428.469535]  process_one_work+0x1b1/0x329
[  428.469541]  worker_thread+0x213/0x372
[  428.469547]  kthread+0x150/0x15f
[  428.469552]  ? pr_cont_work+0x58/0x58
[  428.469558]  ? kthread_blkcg+0x31/0x31

Tested-on: QCA6174 hw3.2 PCI WLAN.RM.4.4.1-00288-QCARMSWPZ-1
Co-developed-by: Wen Gong <quic_wgong@quicinc.com>
Signed-off-by: Wen Gong <quic_wgong@quicinc.com>
Signed-off-by: Abhishek Kumar <kuabhs@chromium.org>
---

Changes in v2:
- Fixed typo, replaced ath11k by ath10k in the comments.
- Adjusted the position of my S-O-B tag.
- Added the Tested-on tag.

 drivers/net/wireless/ath/ath10k/mac.c | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/ath/ath10k/mac.c b/drivers/net/wireless/ath/ath10k/mac.c
index d804e19a742a..e9c1f11fef0a 100644
--- a/drivers/net/wireless/ath/ath10k/mac.c
+++ b/drivers/net/wireless/ath/ath10k/mac.c
@@ -5345,8 +5345,22 @@ static void ath10k_stop(struct ieee80211_hw *hw)
 
 	mutex_lock(&ar->conf_mutex);
 	if (ar->state != ATH10K_STATE_OFF) {
-		if (!ar->hw_rfkill_on)
-			ath10k_halt(ar);
+		if (!ar->hw_rfkill_on) {
+			/* If the current driver state is RESTARTING but not yet
+			 * fully RESTARTED because of incoming suspend event,
+			 * then ath10k_halt is already called via
+			 * ath10k_core_restart and should not be called here.
+			 */
+			if (ar->state != ATH10K_STATE_RESTARTING)
+				ath10k_halt(ar);
+			else
+				/* Suspending here, because when in RESTARTING
+				 * state, ath10k_core_stop skips
+				 * ath10k_wait_for_suspend.
+				 */
+				ath10k_wait_for_suspend(ar,
+							WMI_PDEV_SUSPEND_AND_DISABLE_INTR);
+		}
 		ar->state = ATH10K_STATE_OFF;
 	}
 	mutex_unlock(&ar->conf_mutex);
-- 
2.36.0.464.gb9c8b46e94-goog