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drm: kill BKL from common code

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This restricts the use of the big kernel lock to the i830 and i810
device drivers. The three remaining users in common code (open, ioctl
and release) get converted to a new mutex, the drm_global_mutex,
making the locking stricter than the big kernel lock.

This may have a performance impact, but only in those cases that
currently don't use DRM_UNLOCKED flag in the ioctl list and would
benefit from that anyway.

The reason why i810 and i830 cannot use drm_global_mutex in their
mmap functions is a lock-order inversion problem between the current
use of the BKL and mmap_sem in these drivers. Since the BKL has
release-on-sleep semantics, it's harmless but it would cause trouble
if we replace the BKL with a mutex.

Instead, these drivers get their own ioctl wrappers that take the
BKL around every ioctl call and then set their own handlers as
DRM_UNLOCKED.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: David Airlie <airlied@linux.ie>
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Dave Airlie <airlied@redhat.com>
This commit is contained in:
Arnd Bergmann
2010-07-10 23:51:39 +02:00
committed by Dave Airlie
parent a1e09b6259
commit 58374713c9
9 changed files with 75 additions and 46 deletions
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42
drivers/gpu/drm/i830/i830_dma.c
View File

@@ -36,6 +36,7 @@
#include "i830_drm.h"
#include "i830_drv.h"
#include <linux/interrupt.h> /* For task queue support */
#include <linux/smp_lock.h>
#include <linux/pagemap.h>
#include <linux/delay.h>
#include <linux/slab.h>
@@ -1509,21 +1510,34 @@ int i830_driver_dma_quiescent(struct drm_device *dev)
return 0;
}
/*
* call the drm_ioctl under the big kernel lock because
* to lock against the i830_mmap_buffers function.
*/
long i830_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
int ret;
lock_kernel();
ret = drm_ioctl(file, cmd, arg);
unlock_kernel();
return ret;
}
struct drm_ioctl_desc i830_ioctls[] = {
DRM_IOCTL_DEF(DRM_I830_INIT, i830_dma_init, DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY),
DRM_IOCTL_DEF(DRM_I830_VERTEX, i830_dma_vertex, DRM_AUTH),
DRM_IOCTL_DEF(DRM_I830_CLEAR, i830_clear_bufs, DRM_AUTH),
DRM_IOCTL_DEF(DRM_I830_FLUSH, i830_flush_ioctl, DRM_AUTH),
DRM_IOCTL_DEF(DRM_I830_GETAGE, i830_getage, DRM_AUTH),
DRM_IOCTL_DEF(DRM_I830_GETBUF, i830_getbuf, DRM_AUTH),
DRM_IOCTL_DEF(DRM_I830_SWAP, i830_swap_bufs, DRM_AUTH),
DRM_IOCTL_DEF(DRM_I830_COPY, i830_copybuf, DRM_AUTH),
DRM_IOCTL_DEF(DRM_I830_DOCOPY, i830_docopy, DRM_AUTH),
DRM_IOCTL_DEF(DRM_I830_FLIP, i830_flip_bufs, DRM_AUTH),
DRM_IOCTL_DEF(DRM_I830_IRQ_EMIT, i830_irq_emit, DRM_AUTH),
DRM_IOCTL_DEF(DRM_I830_IRQ_WAIT, i830_irq_wait, DRM_AUTH),
DRM_IOCTL_DEF(DRM_I830_GETPARAM, i830_getparam, DRM_AUTH),
DRM_IOCTL_DEF(DRM_I830_SETPARAM, i830_setparam, DRM_AUTH)
DRM_IOCTL_DEF(DRM_I830_INIT, i830_dma_init, DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY|DRM_UNLOCKED),
DRM_IOCTL_DEF(DRM_I830_VERTEX, i830_dma_vertex, DRM_AUTH|DRM_UNLOCKED),
DRM_IOCTL_DEF(DRM_I830_CLEAR, i830_clear_bufs, DRM_AUTH|DRM_UNLOCKED),
DRM_IOCTL_DEF(DRM_I830_FLUSH, i830_flush_ioctl, DRM_AUTH|DRM_UNLOCKED),
DRM_IOCTL_DEF(DRM_I830_GETAGE, i830_getage, DRM_AUTH|DRM_UNLOCKED),
DRM_IOCTL_DEF(DRM_I830_GETBUF, i830_getbuf, DRM_AUTH|DRM_UNLOCKED),
DRM_IOCTL_DEF(DRM_I830_SWAP, i830_swap_bufs, DRM_AUTH|DRM_UNLOCKED),
DRM_IOCTL_DEF(DRM_I830_COPY, i830_copybuf, DRM_AUTH|DRM_UNLOCKED),
DRM_IOCTL_DEF(DRM_I830_DOCOPY, i830_docopy, DRM_AUTH|DRM_UNLOCKED),
DRM_IOCTL_DEF(DRM_I830_FLIP, i830_flip_bufs, DRM_AUTH|DRM_UNLOCKED),
DRM_IOCTL_DEF(DRM_I830_IRQ_EMIT, i830_irq_emit, DRM_AUTH|DRM_UNLOCKED),
DRM_IOCTL_DEF(DRM_I830_IRQ_WAIT, i830_irq_wait, DRM_AUTH|DRM_UNLOCKED),
DRM_IOCTL_DEF(DRM_I830_GETPARAM, i830_getparam, DRM_AUTH|DRM_UNLOCKED),
DRM_IOCTL_DEF(DRM_I830_SETPARAM, i830_setparam, DRM_AUTH|DRM_UNLOCKED),
};
int i830_max_ioctl = DRM_ARRAY_SIZE(i830_ioctls);