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| author |   Subhash Jadavani <subhashj@codeaurora.org> | 2018-05-03 16:37:18 +0530 |
|---|---|---|
| committer |   Martin K. Petersen <martin.petersen@oracle.com> | 2018-05-18 12:20:48 -0400 |
| commit | 38135535dcc25af856336fda31aeef79d8ad9dab (patch) | |
| tree | 8e1b74cad3a3f72ba6aec9f9b98d1ac9be5faff9 /drivers/scsi/ufs/ufshcd.h | |
| parent | scsi: ufs: ufshcd: fix possible unclocked register access (diff) | |
| download | linux-dev-38135535dcc25af856336fda31aeef79d8ad9dab.tar.xz linux-dev-38135535dcc25af856336fda31aeef79d8ad9dab.zip | |
scsi: ufs: add reference counting for scsi block requests
Currently we call the scsi_block_requests()/scsi_unblock_requests()
whenever we want to block/unblock scsi requests but as there is no
reference counting, nesting of these calls could leave us in undesired
state sometime. Consider following call flow sequence:
1. func1() calls scsi_block_requests() but calls func2() before
calling scsi_unblock_requests()
2. func2() calls scsi_block_requests()
3. func2() calls scsi_unblock_requests()
4. func1() calls scsi_unblock_requests()
As there is no reference counting, we will have scsi requests unblocked
after #3 instead of it to be unblocked only after #4. Though we may not
have failures seen with this, we might run into some failures in future.
Better solution would be to fix this by adding reference counting.
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
Signed-off-by: Can Guo <cang@codeaurora.org>
Signed-off-by: Asutosh Das <asutoshd@codeaurora.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers/scsi/ufs/ufshcd.h')
| -rw-r--r-- | drivers/scsi/ufs/ufshcd.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h index 53121fd6c287..a44b9f45ddd2 100644 --- a/drivers/scsi/ufs/ufshcd.h +++ b/drivers/scsi/ufs/ufshcd.h @@ -499,6 +499,7 @@ struct ufs_stats { * @urgent_bkops_lvl: keeps track of urgent bkops level for device * @is_urgent_bkops_lvl_checked: keeps track if the urgent bkops level for * device is known or not. + * @scsi_block_reqs_cnt: reference counting for scsi block requests */ struct ufs_hba { void __iomem *mmio_base; @@ -699,6 +700,7 @@ struct ufs_hba { struct rw_semaphore clk_scaling_lock; struct ufs_desc_size desc_size; + atomic_t scsi_block_reqs_cnt; }; /* Returns true if clocks can be gated. Otherwise false */ |