Hi Bart,
On Tue, Aug 2, 2022 at 1:34 AM Bart Van Assche <bvanassche@xxxxxxx> wrote:
>
> On 7/30/22 00:08, Stanley Chu wrote:
> > Hi Bart,
> >
> > On Sat, Jul 30, 2022 at 4:12 AM Bart Van Assche <bvanassche@xxxxxxx> wrote:
> >>
> >> On 7/29/22 00:55, Stanley Chu wrote:
> >>> diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
> >>> index 581d88af07ab..dc57a7988023 100644
> >>> --- a/drivers/ufs/core/ufshcd.c
> >>> +++ b/drivers/ufs/core/ufshcd.c
> >>> @@ -1574,8 +1574,6 @@ static ssize_t ufshcd_clkscale_enable_store(struct device *dev,
> >>> ufshcd_rpm_get_sync(hba);
> >>> ufshcd_hold(hba, false);
> >>>
> >>> - hba->clk_scaling.is_enabled = value;
> >>> -
> >>> if (value) {
> >>> ufshcd_resume_clkscaling(hba);
> >>> } else {
> >>> @@ -1586,6 +1584,8 @@ static ssize_t ufshcd_clkscale_enable_store(struct device *dev,
> >>> __func__, err);
> >>> }
> >>>
> >>> + hba->clk_scaling.is_enabled = value;
> >>> +
> >>> ufshcd_release(hba);
> >>> ufshcd_rpm_put_sync(hba);
> >>> out:
> >>> @@ -7259,7 +7259,8 @@ static int ufshcd_host_reset_and_restore(struct ufs_hba *hba)
> >>> hba->silence_err_logs = false;
> >>>
> >>> /* scale up clocks to max frequency before full reinitialization */
> >>> - ufshcd_scale_clks(hba, true);
> >>> + if (ufshcd_is_clkscaling_supported(hba) && hba->clk_scaling.is_enabled)
> >>> + ufshcd_scale_clks(hba, true);
> >>>
> >>> err = ufshcd_hba_enable(hba);
> >>
> >> I see a race condition between the hba->clk_scaling.is_enabled check in
> >> ufshcd_host_reset_and_restore() and the code that sets
> >> ufshcd_clkscale_enable_store(). Shouldn't the code in
> >> ufshcd_host_reset_and_restore() that scales up the clocks be serialized
> >> against ufshcd_clkscale_enable_store()?
> >
> > Both check and set paths are serialized by hba->host_sem currently.
> >
> > Would I miss any other unserialized paths?
>
> Where in ufshcd_host_reset_and_restore() or in its callers is
> hba->host_sem obtained? I don't see it. Am I perhaps overlooking something?
It looks like that some callers do not obtain hba->host_sem. I will
fix this in the next version.
The direct callers of ufshcd_host_reset_and_restore() are,
- ufshcd_link_recovery(), host_sem is obtained by its callers:
ufshcd_err_handler() and ufshcd_wl_resume()
- ufshcd_reset_and_restore(): the same as above
- __ufshcd_wl_suspend(): host_sem is obtained by the caller
ufshcd_wl_suspend() but not obtained by other callers.
Thanks,
Stanley
