[PATCH v2 16/20] scsi: ufs: Fix a kernel crash during shutdown

Bart Van Assche
2021-11-19T19:58:48Z

Fix the following kernel crash:

Unable to handle kernel paging request at virtual address ffffffc91e735000
Call trace:
__queue_work+0x26c/0x624
queue_work_on+0x6c/0xf0
ufshcd_hold+0x12c/0x210
__ufshcd_wl_suspend+0xc0/0x400
ufshcd_wl_shutdown+0xb8/0xcc
device_shutdown+0x184/0x224
kernel_restart+0x4c/0x124
__arm64_sys_reboot+0x194/0x264
el0_svc_common+0xc8/0x1d4
do_el0_svc+0x30/0x8c
el0_svc+0x20/0x30
el0_sync_handler+0x84/0xe4
el0_sync+0x1bc/0x1c0

Fix this crash by ungating the clock before destroying the work queue
on which clock gating work is queued.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
drivers/scsi/ufs/ufshcd.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 7e27d6436889..6a743da7d2db 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -1667,7 +1667,8 @@ int ufshcd_hold(struct ufs_hba *hba, bool async)
bool flush_result;
unsigned long flags;

- if (!ufshcd_is_clkgating_allowed(hba))
+ if (!ufshcd_is_clkgating_allowed(hba) ||
+ !hba->clk_gating.is_initialized)
goto out;
spin_lock_irqsave(hba->host->host_lock, flags);
hba->clk_gating.active_reqs++;
@@ -1827,7 +1828,7 @@ static void __ufshcd_release(struct ufs_hba *hba)

if (hba->clk_gating.active_reqs || hba->clk_gating.is_suspended ||
hba->ufshcd_state != UFSHCD_STATE_OPERATIONAL ||
- hba->outstanding_tasks ||
+ hba->outstanding_tasks || !hba->clk_gating.is_initialized ||
hba->active_uic_cmd || hba->uic_async_done ||
hba->clk_gating.state == CLKS_OFF)
return;
@@ -1962,11 +1963,15 @@ static void ufshcd_exit_clk_gating(struct ufs_hba *hba)
{
if (!hba->clk_gating.is_initialized)
return;
+
ufshcd_remove_clk_gating_sysfs(hba);
- cancel_work_sync(&hba->clk_gating.ungate_work);
- cancel_delayed_work_sync(&hba->clk_gating.gate_work);
- destroy_workqueue(hba->clk_gating.clk_gating_workq);
+
+ /* Ungate the clock if necessary. */
+ ufshcd_hold(hba, false);
hba->clk_gating.is_initialized = false;
+ ufshcd_release(hba);
+
+ destroy_workqueue(hba->clk_gating.clk_gating_workq);
}

/* Must be called with host lock acquired */