Re: [PATCH] scsi: ufs: add missing host_lock in setup_xfer_req

[Bart Van Assche]

On 7/13/21 12:45 PM, Bean Huo wrote:
> This change only impacts on the Samsung exynos platform. and Can's
> optimization patch is to optimise the host_lock,, and removed
> host_lock, now add back in this function makes sense to me.
> but I am thinking how about hba->host_sem?

Hi Bean,

Calls of exynos_ufs_specify_nexus_t_xfer_req() must be serialized, hence 
Jaegeuks' patch. This function is called from the I/O submission path so 
performance matters. My understanding is that spinlocks have less 
overhead than semaphores. Hence the choice for a spinlock.

Thanks,

Bart.