[PATCH 01/20] drm/i810: remove the BKL

Arnd Bergmann
2011-01-25T22:17:53Z

SMP i810 systems were practically nonexistent and the configuration
was not officially supported by Intel at the time when Pentium-III
was common.

With this change, it is still possible to build a distribution kernel
that has support for SMP and includes the i810 driver without the BKL.
As a precaution, check for the theoretical SMP case at run time and
refuse to load the driver.

We also need to disable CONFIG_PREEMPT builds for this driver.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Dave Airlie <airlied@linux.ie>
Cc: dri-devel@lists.freedesktop.org
---
drivers/gpu/drm/Kconfig | 4 ++--
drivers/gpu/drm/i810/i810_dma.c | 18 +-----------------
drivers/gpu/drm/i810/i810_drv.c | 6 +++++-
3 files changed, 8 insertions(+), 20 deletions(-)

diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index bea966f..9fc650d 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -73,8 +73,8 @@ source "drivers/gpu/drm/radeon/Kconfig"

config DRM_I810
tristate "Intel I810"
- # BKL usage in order to avoid AB-BA deadlocks, may become BROKEN_ON_SMP
- depends on DRM && AGP && AGP_INTEL && BKL
+ # !PREEMPT because of missing ioctl locking
+ depends on DRM && AGP && AGP_INTEL && (!PREEMPT || BROKEN)
help
Choose this option if you have an Intel I810 graphics card. If M is
selected, the module will be called i810. AGP support is required
diff --git a/drivers/gpu/drm/i810/i810_dma.c b/drivers/gpu/drm/i810/i810_dma.c
index ff33e53..8f371e8 100644
--- a/drivers/gpu/drm/i810/i810_dma.c
+++ b/drivers/gpu/drm/i810/i810_dma.c
@@ -37,7 +37,6 @@
#include <linux/interrupt.h> /* For task queue support */
#include <linux/delay.h>
#include <linux/slab.h>
-#include <linux/smp_lock.h>
#include <linux/pagemap.h>

#define I810_BUF_FREE 2
@@ -94,7 +93,6 @@ static int i810_mmap_buffers(struct file *filp, struct vm_area_struct *vma)
struct drm_buf *buf;
drm_i810_buf_priv_t *buf_priv;

- lock_kernel();
dev = priv->minor->dev;
dev_priv = dev->dev_private;
buf = dev_priv->mmap_buffer;
@@ -104,7 +102,6 @@ static int i810_mmap_buffers(struct file *filp, struct vm_area_struct *vma)
vma->vm_file = filp;

buf_priv->currently_mapped = I810_BUF_MAPPED;
- unlock_kernel();

if (io_remap_pfn_range(vma, vma->vm_start,
vma->vm_pgoff,
@@ -116,7 +113,7 @@ static int i810_mmap_buffers(struct file *filp, struct vm_area_struct *vma)
static const struct file_operations i810_buffer_fops = {
.open = drm_open,
.release = drm_release,
- .unlocked_ioctl = i810_ioctl,
+ .unlocked_ioctl = drm_ioctl,
.mmap = i810_mmap_buffers,
.fasync = drm_fasync,
.llseek = noop_llseek,
@@ -1242,19 +1239,6 @@ int i810_driver_dma_quiescent(struct drm_device *dev)
return 0;
}

-/*
- * call the drm_ioctl under the big kernel lock because
- * to lock against the i810_mmap_buffers function.
- */
-long i810_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 i810_ioctls[] = {
DRM_IOCTL_DEF_DRV(I810_INIT, i810_dma_init, DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY|DRM_UNLOCKED),
DRM_IOCTL_DEF_DRV(I810_VERTEX, i810_dma_vertex, DRM_AUTH|DRM_UNLOCKED),
diff --git a/drivers/gpu/drm/i810/i810_drv.c b/drivers/gpu/drm/i810/i810_drv.c
index 88bcd33..0152fa2 100644
--- a/drivers/gpu/drm/i810/i810_drv.c
+++ b/drivers/gpu/drm/i810/i810_drv.c
@@ -57,7 +57,7 @@ static struct drm_driver driver = {
.owner = THIS_MODULE,
.open = drm_open,
.release = drm_release,
- .unlocked_ioctl = i810_ioctl,
+ .unlocked_ioctl = drm_ioctl,
.mmap = drm_mmap,
.poll = drm_poll,
.fasync = drm_fasync,
@@ -79,6 +79,10 @@ static struct drm_driver driver = {

static int __init i810_init(void)
{
+ if (num_possible_cpus() > 1) {
+ pr_err("drm/i810 does not support SMP\n");
+ return -EINVAL;
+ }
driver.num_ioctls = i810_max_ioctl;
return drm_init(&driver);
}
--
1.7.1