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scsi: ufs: Fix a deadlock in the error handler
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commit 945c3cc 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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@bvanassche @gregkh
bvanassche authored and gregkh committed Feb 23, 2022
1 parent 2af0fdf commit 493c9e8
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Showing 2 changed files with 16 additions and 39 deletions.
53 changes: 14 additions & 39 deletions drivers/scsi/ufs/ufshcd.c
View file
Expand Up @@ -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 */
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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);
Expand All @@ -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;
}
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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;
}
Expand Down Expand Up @@ -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;
Expand Down
2 changes: 2 additions & 0 deletions drivers/scsi/ufs/ufshcd.h
View file
Expand Up @@ -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
Expand Down Expand Up @@ -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;
Expand Down

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