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authorJeremy Kerr <jk@ozlabs.org>2008-01-11 14:28:04 +0100
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-01-11 11:47:43 -0800
commit8dab63761219d7bc6a7d7d3b5f0fca76af5533a5 (patch)
tree3354b2867c05507acb5618f961cdf982f98e2b41 /drivers/video/ps3fb.c
parentba21611c9c0031ca8388cae5e43b38c29c8b595d (diff)
downloadvexpress-lsk-8dab63761219d7bc6a7d7d3b5f0fca76af5533a5.tar.gz
ps3fb: fix deadlock on kexec()
Since the introduction of the acquire_console_sem calls in 0333d83509c7d8496c8965b5ba9bc0c98e83c259, kexecing can cause the kernel to deadlock: ps3fb_shutdown() -> unregister_framebuffer() -> fb_notifier_call_chain(FB_EVENT_FB_UNBIND) -> fbcon_fb_unbind() -> unbind_con_driver() -> bind_con_driver() [ acquires console_sem ] -> fbcon_deinit() -> fbops->fb_release(newinfo, 0) -> ps3fb_release() -> ps3fb_sync() [ acquires console_sem ] This change avoids the deadlock by moving the acquire_console_sem() out of ps3fb_sync(), and puts it into the two other callsites, leaving ps3fb_release() to call ps3fb_sync() without the console semaphore. [Geert] - Corrected call sequence above - ps3fb_release() may be called with and without console_sem held. This is an inconsistency that should be fixed at the fb level, but for now, try to acquire console_sem in ps3fb_release(). I think it's safer to let ps3fb_release() try to acquire console_sem and not refresh the screen if it fails, than to call ps3fb_sync() without holding console_sem, as ps3fb_par may be modified at the same time, causing crashes or lockups. Besides, ps3fb_release() only calls ps3fb_sync() to refresh the screen when display flipping is disabled, which is an uncommon case (except during shutdown/kexec). Signed-off-by: Jeremy Kerr <jk@ozlabs.org> Signed-off-by: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/video/ps3fb.c')
-rw-r--r--drivers/video/ps3fb.c12
1 files changed, 8 insertions, 4 deletions
diff --git a/drivers/video/ps3fb.c b/drivers/video/ps3fb.c
index ae07e02943d..044a423a72c 100644
--- a/drivers/video/ps3fb.c
+++ b/drivers/video/ps3fb.c
@@ -443,8 +443,6 @@ static int ps3fb_sync(struct fb_info *info, u32 frame)
u32 ddr_line_length, xdr_line_length;
u64 ddr_base, xdr_base;
- acquire_console_sem();
-
if (frame > par->num_frames - 1) {
dev_dbg(info->device, "%s: invalid frame number (%u)\n",
__func__, frame);
@@ -464,7 +462,6 @@ static int ps3fb_sync(struct fb_info *info, u32 frame)
xdr_line_length);
out:
- release_console_sem();
return error;
}
@@ -479,7 +476,10 @@ static int ps3fb_release(struct fb_info *info, int user)
if (atomic_dec_and_test(&ps3fb.f_count)) {
if (atomic_read(&ps3fb.ext_flip)) {
atomic_set(&ps3fb.ext_flip, 0);
- ps3fb_sync(info, 0); /* single buffer */
+ if (!try_acquire_console_sem()) {
+ ps3fb_sync(info, 0); /* single buffer */
+ release_console_sem();
+ }
}
}
return 0;
@@ -865,7 +865,9 @@ static int ps3fb_ioctl(struct fb_info *info, unsigned int cmd,
break;
dev_dbg(info->device, "PS3FB_IOCTL_FSEL:%d\n", val);
+ acquire_console_sem();
retval = ps3fb_sync(info, val);
+ release_console_sem();
break;
default:
@@ -885,7 +887,9 @@ static int ps3fbd(void *arg)
set_current_state(TASK_INTERRUPTIBLE);
if (ps3fb.is_kicked) {
ps3fb.is_kicked = 0;
+ acquire_console_sem();
ps3fb_sync(info, 0); /* single buffer */
+ release_console_sem();
}
schedule();
}