Re: [PATCH v3 15/17] scsi: ufs: Stop using the clock scaling lock in the error handler
From: Adrian Hunter <adrian.hunter@intel.com>
Date: 2021-12-01 14:08:21
On 01/12/2021 01:33, Bart Van Assche wrote:
Instead of locking and unlocking the clock scaling lock, surround the command queueing code with an RCU reader lock and call synchronize_rcu(). This patch prepares for removal of the clock scaling lock. Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>
quoted hunk ↗ jump to hunk
--- drivers/scsi/ufs/ufshcd.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c index 074ea9ae54e0..c4cf5c4b4893 100644 --- a/drivers/scsi/ufs/ufshcd.c +++ b/drivers/scsi/ufs/ufshcd.c@@ -2684,6 +2684,12 @@ static int ufshcd_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *cmd) if (!down_read_trylock(&hba->clk_scaling_lock)) return SCSI_MLQUEUE_HOST_BUSY; + /* + * Allows the UFS error handler to wait for prior ufshcd_queuecommand() + * calls. + */ + rcu_read_lock(); + switch (hba->ufshcd_state) { case UFSHCD_STATE_OPERATIONAL: break;@@ -2762,7 +2768,10 @@ static int ufshcd_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *cmd) } ufshcd_send_command(hba, tag); + out: + rcu_read_unlock(); + up_read(&hba->clk_scaling_lock); if (ufs_trigger_eh()) {@@ -5951,8 +5960,7 @@ static void ufshcd_err_handling_prepare(struct ufs_hba *hba) } ufshcd_scsi_block_requests(hba); /* Drain ufshcd_queuecommand() */ - down_write(&hba->clk_scaling_lock); - up_write(&hba->clk_scaling_lock); + synchronize_rcu(); cancel_work_sync(&hba->eeh_work); }