[PATCH 8/8] scsi: ufs: Check for completion from the timeout handler

Bart Van Assche
2024-06-17T21:10:06Z

If ufshcd_abort() returns SUCCESS for an already completed command then
that command is completed twice. This results in a crash. Prevent this by
checking whether a command has completed without completion interrupt from
the timeout handler. This CL fixes the following kernel crash:

Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
Call trace:
dma_direct_map_sg+0x70/0x274
scsi_dma_map+0x84/0x124
ufshcd_queuecommand+0x3fc/0x880
scsi_queue_rq+0x7d0/0x111c
blk_mq_dispatch_rq_list+0x440/0xebc
blk_mq_do_dispatch_sched+0x5a4/0x6b8
__blk_mq_sched_dispatch_requests+0x150/0x220
__blk_mq_run_hw_queue+0xf0/0x218
__blk_mq_delay_run_hw_queue+0x8c/0x18c
blk_mq_run_hw_queue+0x1a4/0x360
blk_mq_sched_insert_requests+0x130/0x334
blk_mq_flush_plug_list+0x138/0x234
blk_flush_plug_list+0x118/0x164
blk_finish_plug()
read_pages+0x38c/0x408
page_cache_ra_unbounded+0x230/0x2f8
do_sync_mmap_readahead+0x1a4/0x208
filemap_fault+0x27c/0x8f4
f2fs_filemap_fault+0x28/0xfc
__do_fault+0xc4/0x208
handle_pte_fault+0x290/0xe04
do_handle_mm_fault+0x52c/0x858
do_page_fault+0x5dc/0x798
do_translation_fault+0x40/0x54
do_mem_abort+0x60/0x134
el0_da+0x40/0xb8
el0t_64_sync_handler+0xc4/0xe4
el0t_64_sync+0x1b4/0x1b8

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
drivers/ufs/core/ufshcd.c | 23 ++++++++++++++++++++++-
1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index e3835e61e4b1..47cc0802c4f4 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -8922,7 +8922,28 @@ static void ufshcd_async_scan(void *data, async_cookie_t cookie)

static enum scsi_timeout_action ufshcd_eh_timed_out(struct scsi_cmnd *scmd)
{
- struct ufs_hba *hba = shost_priv(scmd->device->host);
+ struct scsi_device *sdev = scmd->device;
+ struct ufs_hba *hba = shost_priv(sdev->host);
+ struct scsi_cmnd *cmd2 = scmd;
+ const u32 unique_tag = blk_mq_unique_tag(scsi_cmd_to_rq(scmd));
+
+ WARN_ON_ONCE(!scmd);
+
+ if (is_mcq_enabled(hba)) {
+ struct request *rq = scsi_cmd_to_rq(scmd);
+ struct ufs_hw_queue *hwq = ufshcd_mcq_req_to_hwq(hba, rq);
+
+ ufshcd_mcq_poll_cqe_lock(hba, hwq, &cmd2);
+ } else {
+ __ufshcd_poll(hba->host, UFSHCD_POLL_FROM_INTERRUPT_CONTEXT,
+ &cmd2);
+ }
+ if (cmd2 == NULL) {
+ sdev_printk(KERN_INFO, sdev,
+ "%s: cmd with tag %#x has already been completed\n",
+ __func__, unique_tag);
+ return SCSI_EH_DONE;
+ }

if (!hba->system_suspending) {
/* Activate the error handler in the SCSI core. */