diff options
author | Jeremy Kerr <jk@ozlabs.org> | 2008-01-11 13:28:04 (GMT) |
---|---|---|
committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2008-01-11 19:47:43 (GMT) |
commit | 8dab63761219d7bc6a7d7d3b5f0fca76af5533a5 (patch) | |
tree | 3354b2867c05507acb5618f961cdf982f98e2b41 | |
parent | ba21611c9c0031ca8388cae5e43b38c29c8b595d (diff) | |
download | linux-8dab63761219d7bc6a7d7d3b5f0fca76af5533a5.tar.xz |
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>
-rw-r--r-- | drivers/video/ps3fb.c | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/drivers/video/ps3fb.c b/drivers/video/ps3fb.c index ae07e02..044a423 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(); } |