scsi: ufshcd: Fix race between clk scaling and ungate work

The ungate work turns on the clock before it exits hibern8, if the link was put in hibern8 during clock gating work. There occurs a race condition when clock scaling work calls ufshcd_hold() to make sure low power states cannot be entered, but that returns by checking only whether the clocks are on. This causes the clock scaling work to issue UIC commands when the link is in hibern8 causing failures. Make sure we exit hibern8 state before returning from ufshcd_hold(). Callstacks for race condition: ufshcd_scale_gear ufshcd_devfreq_scale ufshcd_devfreq_target update_devfreq devfreq_monitor process_one_work worker_thread kthread ret_from_fork ufshcd_uic_hibern8_exit ufshcd_ungate_work process_one_work worker_thread kthread ret_from_fork Signed-off-by: Venkat Gopalakrishnan <venkatg@codeaurora.org> Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
1 files changed, 15 insertions, 0 deletions
diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
tree	5b18a94f664b3b676f5ae1352f52f37a09d848fd
parent	8643ae66ce749f63ea0de928f5059b7b5f8b30cd (diff)