Re: [RFC PATCH v1 1/2] scsi: ufs: introduce vendor isr

Bart Van Assche
2021-08-06T16:18:41Z

On 8/5/21 11:34 PM, Kiwoong Kim wrote:
> This patch is to activate some interrupt sources
> that aren't defined in UFSHCI specifications. Those
> purpose could be error handling, workaround or whatever.
>
> Signed-off-by: Kiwoong Kim <kwmad.kim@samsung.com>
> ---
> drivers/scsi/ufs/ufshcd.c | 10 ++++++++++
> drivers/scsi/ufs/ufshcd.h | 8 ++++++++
> 2 files changed, 18 insertions(+)
>
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index 05495c34a2b7..f85a9b335e0b 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -6428,6 +6428,16 @@ static irqreturn_t ufshcd_tmc_handler(struct ufs_hba *hba)
> static irqreturn_t ufshcd_sl_intr(struct ufs_hba *hba, u32 intr_status)
> {
> irqreturn_t retval = IRQ_NONE;
> + int res = 0;
> + unsigned long flags;
> +
> + retval = ufshcd_vops_intr(hba, &res);
> + if (res) {
> + spin_lock_irqsave(hba->host->host_lock, flags);
> + hba->force_reset = true;
> + ufshcd_schedule_eh_work(hba);
> + spin_unlock_irqrestore(hba->host->host_lock, flags);
> + }

How can a non-standard extension have error handling code in common
code? Please move the code under if (res) into the vendor code.

> if (intr_status & UFSHCD_UIC_MASK)
> retval |= ufshcd_uic_cmd_compl(hba, intr_status);
> diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
> index 971cfabc4a1e..1ed0a911f864 100644
> --- a/drivers/scsi/ufs/ufshcd.h
> +++ b/drivers/scsi/ufs/ufshcd.h
> @@ -356,6 +356,7 @@ struct ufs_hba_variant_ops {
> const union ufs_crypto_cfg_entry *cfg, int slot);
> void (*event_notify)(struct ufs_hba *hba,
> enum ufs_event_type evt, void *data);
> + irqreturn_t (*intr)(struct ufs_hba *hba, int *res);
> };
>
> /* clock gating state */
> @@ -1296,6 +1297,13 @@ static inline void ufshcd_vops_config_scaling_param(struct ufs_hba *hba,
> hba->vops->config_scaling_param(hba, profile, data);
> }
>
> +static inline irqreturn_t ufshcd_vops_intr(struct ufs_hba *hba, int *res)
> +{
> + if (hba->vops && hba->vops->intr)
> + return hba->vops->intr(hba, res);
> + return IRQ_NONE;
> +}
> +
> extern struct ufs_pm_lvl_states ufs_pm_lvl_states[];

So this code adds an indirect function call in the interrupt handler?
This will have a negative impact on performance, especially on a kernel
with security mitigations enabled. See also
https://lwn.net/Articles/774743/.

Thanks,

Bart.