Re: [PATCH 1/2] drm/vmwgfx: Drop preempt_disable() in vmw_fifo_ping_host()

On Mon, 2020-02-24 at 15:07 +0100, Sebastian Andrzej Siewior wrote:

vmw_fifo_ping_host() disables preemption around a test and a register write via vmw_write(). The write function acquires a spinlock_t typed lock which is not allowed in a preempt_disable()ed section on PREEMPT_RT. This has been reported in the bugzilla.

It has been explained by Thomas Hellstrom that this preempt_disable()ed section is not required for correctness.

Remove the preempt_disable() section.

Hi, Sebastian,

I suppose there isn't something like a preempt_disable_unless_RT() macro?

If not, Reviewed-by: Thomas Hellstrom thellstrom@vmware.com

I'll include in the next vmwgfx-next pull request

Thanks, Thomas