commit 945c3cca05d78351bba29fa65d93834cb7934c7b upstream.

The following deadlock has been observed on a test setup:

- All tags allocated

- The SCSI error handler calls ufshcd_eh_host_reset_handler()

- ufshcd_eh_host_reset_handler() queues work that calls ufshcd_err_handler()

- ufshcd_err_handler() locks up as follows:

Workqueue: ufs_eh_wq_0 ufshcd_err_handler.cfi_jt Call trace: __switch_to+0x298/0x5d8 __schedule+0x6cc/0xa94 schedule+0x12c/0x298 blk_mq_get_tag+0x210/0x480 __blk_mq_alloc_request+0x1c8/0x284 blk_get_request+0x74/0x134 ufshcd_exec_dev_cmd+0x68/0x640 ufshcd_verify_dev_init+0x68/0x35c ufshcd_probe_hba+0x12c/0x1cb8 ufshcd_host_reset_and_restore+0x88/0x254 ufshcd_reset_and_restore+0xd0/0x354 ufshcd_err_handler+0x408/0xc58 process_one_work+0x24c/0x66c worker_thread+0x3e8/0xa4c kthread+0x150/0x1b4 ret_from_fork+0x10/0x30

Fix this lockup by making ufshcd_exec_dev_cmd() allocate a reserved request.

Link: https://lore.kernel.org/r/20211203231950.193369-10-bvanassche@acm.org Tested-by: Bean Huo beanhuo@micron.com Reviewed-by: Adrian Hunter adrian.hunter@intel.com Reviewed-by: Bean Huo beanhuo@micron.com Signed-off-by: Bart Van Assche bvanassche@acm.org Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Bart Van Assche bvanassche@acm.org --- drivers/scsi/ufs/ufshcd.c | 53 +++++++++++---------------------------- drivers/scsi/ufs/ufshcd.h | 2 ++ 2 files changed, 16 insertions(+), 39 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c index 92e4f0dbb791..cdec85bcc4cc 100644 --- a/drivers/scsi/ufs/ufshcd.c +++ b/drivers/scsi/ufs/ufshcd.c @@ -125,8 +125,9 @@ EXPORT_SYMBOL_GPL(ufshcd_dump_regs); enum { UFSHCD_MAX_CHANNEL = 0, UFSHCD_MAX_ID = 1, - UFSHCD_CMD_PER_LUN = 32, - UFSHCD_CAN_QUEUE = 32, + UFSHCD_NUM_RESERVED = 1, + UFSHCD_CMD_PER_LUN = 32 - UFSHCD_NUM_RESERVED, + UFSHCD_CAN_QUEUE = 32 - UFSHCD_NUM_RESERVED, };

/* UFSHCD error handling flags */ @@ -2185,6 +2186,7 @@ static inline int ufshcd_hba_capabilities(struct ufs_hba *hba) hba->nutrs = (hba->capabilities & MASK_TRANSFER_REQUESTS_SLOTS) + 1; hba->nutmrs = ((hba->capabilities & MASK_TASK_MANAGEMENT_REQUEST_SLOTS) >> 16) + 1; + hba->reserved_slot = hba->nutrs - 1;

/* Read crypto capabilities */ err = ufshcd_hba_init_crypto_capabilities(hba); @@ -2910,30 +2912,15 @@ static int ufshcd_wait_for_dev_cmd(struct ufs_hba *hba, static int ufshcd_exec_dev_cmd(struct ufs_hba *hba, enum dev_cmd_type cmd_type, int timeout) { - struct request_queue *q = hba->cmd_queue; DECLARE_COMPLETION_ONSTACK(wait); - struct request *req; + const u32 tag = hba->reserved_slot; struct ufshcd_lrb *lrbp; int err; - int tag;

- down_read(&hba->clk_scaling_lock); + /* Protects use of hba->reserved_slot. */ + lockdep_assert_held(&hba->dev_cmd.lock);

- /* - * Get free slot, sleep if slots are unavailable. - * Even though we use wait_event() which sleeps indefinitely, - * the maximum wait time is bounded by SCSI request timeout. - */ - req = blk_get_request(q, REQ_OP_DRV_OUT, 0); - if (IS_ERR(req)) { - err = PTR_ERR(req); - goto out_unlock; - } - tag = req->tag; - WARN_ONCE(tag < 0, "Invalid tag %d\n", tag); - /* Set the timeout such that the SCSI error handler is not activated. */ - req->timeout = msecs_to_jiffies(2 * timeout); - blk_mq_start_request(req); + down_read(&hba->clk_scaling_lock);

lrbp = &hba->lrb[tag]; WARN_ON(lrbp->cmd); @@ -2951,8 +2938,6 @@ static int ufshcd_exec_dev_cmd(struct ufs_hba *hba, (struct utp_upiu_req *)lrbp->ucd_rsp_ptr);

out: - blk_put_request(req); -out_unlock: up_read(&hba->clk_scaling_lock); return err; } @@ -6640,23 +6625,16 @@ static int ufshcd_issue_devman_upiu_cmd(struct ufs_hba *hba, enum dev_cmd_type cmd_type, enum query_opcode desc_op) { - struct request_queue *q = hba->cmd_queue; DECLARE_COMPLETION_ONSTACK(wait); - struct request *req; + const u32 tag = hba->reserved_slot; struct ufshcd_lrb *lrbp; int err = 0; - int tag; u8 upiu_flags;

- down_read(&hba->clk_scaling_lock); + /* Protects use of hba->reserved_slot. */ + lockdep_assert_held(&hba->dev_cmd.lock);

- req = blk_get_request(q, REQ_OP_DRV_OUT, 0); - if (IS_ERR(req)) { - err = PTR_ERR(req); - goto out_unlock; - } - tag = req->tag; - WARN_ONCE(tag < 0, "Invalid tag %d\n", tag); + down_read(&hba->clk_scaling_lock);

lrbp = &hba->lrb[tag]; WARN_ON(lrbp->cmd); @@ -6725,9 +6703,6 @@ static int ufshcd_issue_devman_upiu_cmd(struct ufs_hba *hba, ufshcd_add_query_upiu_trace(hba, err ? UFS_QUERY_ERR : UFS_QUERY_COMP, (struct utp_upiu_req *)lrbp->ucd_rsp_ptr);

- blk_put_request(req); - -out_unlock: up_read(&hba->clk_scaling_lock); return err; } @@ -9418,8 +9393,8 @@ int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq) /* Configure LRB */ ufshcd_host_memory_configure(hba);

- host->can_queue = hba->nutrs; - host->cmd_per_lun = hba->nutrs; + host->can_queue = hba->nutrs - UFSHCD_NUM_RESERVED; + host->cmd_per_lun = hba->nutrs - UFSHCD_NUM_RESERVED; host->max_id = UFSHCD_MAX_ID; host->max_lun = UFS_MAX_LUNS; host->max_channel = UFSHCD_MAX_CHANNEL; diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h index 07ada6676c3b..d470a52ff24c 100644 --- a/drivers/scsi/ufs/ufshcd.h +++ b/drivers/scsi/ufs/ufshcd.h @@ -725,6 +725,7 @@ struct ufs_hba_monitor { * @capabilities: UFS Controller Capabilities * @nutrs: Transfer Request Queue depth supported by controller * @nutmrs: Task Management Queue depth supported by controller + * @reserved_slot: Used to submit device commands. Protected by @dev_cmd.lock. * @ufs_version: UFS Version to which controller complies * @vops: pointer to variant specific operations * @priv: pointer to variant specific private data @@ -813,6 +814,7 @@ struct ufs_hba { u32 capabilities; int nutrs; int nutmrs; + u32 reserved_slot; u32 ufs_version; const struct ufs_hba_variant_ops *vops; struct ufs_hba_variant_params *vps;