[v5,0/2] bus: mhi: host: Add lock to avoid race when ringing channel DB

Message

Qiang Yu Dec. 11, 2023, 6:42 a.m. UTC

1. We need a write lock in mhi_gen_tre otherwise there is race of the WP
used for ringing channel DB between mhi_queue and M0 transition.
2. We can not invoke local_bh_enable() when irqs are disabled, so move
read_lock_irqsave() under the mhi_gen_tre() since we add write_lock_bh() in
mhi_gen_tre().
3. Unlock xfer_cb to prevent potential lockup

v1 -> v2:
Added write_unlock_bh(&mhi_chan->lock) in mhi_gen_tre() before return
because of error process.

v2 -> v3:
1. split protecting WP and unlocking xfer_cb into two patches
2. Add a new patch to stop processing buffer and eventof a disabled or
stopped channel.

v3 -> v4:
1. Modify commit message
2. Add unlock operation before return error

v4 -> v5:
1. Squash "protecting WP" and "Take irqsave lock" into one patch
2. Drop patch 3/4 of patch v4

Bhaumik Bhatt (1):
  bus: mhi: host: Add spinlock to protect WP access when queueing TREs

Qiang Yu (1):
  bus: mhi: host: Drop chan lock before queuing buffers

 drivers/bus/mhi/host/main.c | 26 +++++++++++++++++---------
 1 file changed, 17 insertions(+), 9 deletions(-)

Comments

Manivannan Sadhasivam Dec. 16, 2023, 5:21 a.m. UTC | #1

On Mon, Dec 11, 2023 at 02:42:50PM +0800, Qiang Yu wrote:
> 
> 1. We need a write lock in mhi_gen_tre otherwise there is race of the WP
> used for ringing channel DB between mhi_queue and M0 transition.
> 2. We can not invoke local_bh_enable() when irqs are disabled, so move
> read_lock_irqsave() under the mhi_gen_tre() since we add write_lock_bh() in
> mhi_gen_tre().
> 3. Unlock xfer_cb to prevent potential lockup
> 

Applied to mhi-next!

- Mani

> v1 -> v2:
> Added write_unlock_bh(&mhi_chan->lock) in mhi_gen_tre() before return
> because of error process.
> 
> v2 -> v3:
> 1. split protecting WP and unlocking xfer_cb into two patches
> 2. Add a new patch to stop processing buffer and eventof a disabled or
> stopped channel.
> 
> v3 -> v4:
> 1. Modify commit message
> 2. Add unlock operation before return error
> 
> v4 -> v5:
> 1. Squash "protecting WP" and "Take irqsave lock" into one patch
> 2. Drop patch 3/4 of patch v4
> 
> Bhaumik Bhatt (1):
>   bus: mhi: host: Add spinlock to protect WP access when queueing TREs
> 
> Qiang Yu (1):
>   bus: mhi: host: Drop chan lock before queuing buffers
> 
>  drivers/bus/mhi/host/main.c | 26 +++++++++++++++++---------
>  1 file changed, 17 insertions(+), 9 deletions(-)
> 
> -- 
> 2.7.4
> 
>