| From: Sebastian Andrzej Siewior <bigeasy@linutronix.de> |
| Date: Fri, 21 Feb 2020 18:57:11 +0100 |
| Subject: [PATCH] drm/vmwgfx: Drop preempt_disable() in |
| vmw_fifo_ping_host() |
| |
| 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. |
| |
| Link: https://bugzilla.kernel.org/show_bug.cgi?id=206591 |
| Link: https://lkml.kernel.org/r/0b5e1c65d89951de993deab06d1d197b40fd67aa.camel@vmware.com |
| Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> |
| --- |
| drivers/gpu/drm/vmwgfx/vmwgfx_fifo.c | 2 -- |
| 1 file changed, 2 deletions(-) |
| |
| --- a/drivers/gpu/drm/vmwgfx/vmwgfx_fifo.c |
| +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_fifo.c |
| @@ -169,10 +169,8 @@ void vmw_fifo_ping_host(struct vmw_priva |
| { |
| u32 *fifo_mem = dev_priv->mmio_virt; |
| |
| - preempt_disable(); |
| if (cmpxchg(fifo_mem + SVGA_FIFO_BUSY, 0, 1) == 0) |
| vmw_write(dev_priv, SVGA_REG_SYNC, reason); |
| - preempt_enable(); |
| } |
| |
| void vmw_fifo_release(struct vmw_private *dev_priv, struct vmw_fifo_state *fifo) |
