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Commit 5fa13e17 authored by Sayali Lokhande's avatar Sayali Lokhande Committed by Gerrit - the friendly Code Review server
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scsi: ufs: Release rw_sem while sending device management requests 



Consider the below scenario:
1. Clock scaling is running
   - releases rw_sem before sending hibern8
    - issues hibern8 enter
      - error in hibern8 [1]
      - triggers error-handler(eh) [3]
   - waits on acquiring rw_sem [5]
2. Exception is raised by device
   - acquires rw_sem (if eh not running)as part of
     sending device management reqs [2]
   - returns whithout releasing rw_sem
   (as eh starts running in between) [4]

Here, [5] waits on [2] which acquires rw_sem but does not release,
as eh[3] starts running in between [2] and [4]. Fix this by releasing
rw_sem in ufshcd_exec_dev_cmd() if it was indeed acquired.

Change-Id: Ic6bb9f25e25bff6b8798bb39ea150e920e5bc1a2
Signed-off-by: default avatarSayali Lokhande <sayalil@codeaurora.org>
parent b29f3404

drivers/scsi/ufs/ufshcd.c

+5 −2
Original line number Diff line number Diff line
@@ -4044,6 +4044,7 @@ static int ufshcd_exec_dev_cmd(struct ufs_hba *hba, 
	int tag;

	struct completion wait;

	unsigned long flags;

	bool has_read_lock = false;



	/*

	 * May get invoked from shutdown and IOCTL contexts.
@@ -4051,8 +4052,10 @@ static int ufshcd_exec_dev_cmd(struct ufs_hba *hba, 
	 * In error recovery context, it may come with lock acquired.

	 */



	if (!ufshcd_is_shutdown_ongoing(hba) && !ufshcd_eh_in_progress(hba))

	if (!ufshcd_is_shutdown_ongoing(hba) && !ufshcd_eh_in_progress(hba)) {

		down_read(&hba->lock);

		has_read_lock = true;

	}



	/*

	 * Get free slot, sleep if slots are unavailable.
@@ -4090,7 +4093,7 @@ static int ufshcd_exec_dev_cmd(struct ufs_hba *hba, 
out_put_tag:

	ufshcd_put_dev_cmd_tag(hba, tag);

	wake_up(&hba->dev_cmd.tag_wq);

	if (!ufshcd_is_shutdown_ongoing(hba) && !ufshcd_eh_in_progress(hba))

	if (has_read_lock)

		up_read(&hba->lock);

	return err;

}