Miles Lane reported the following error:
2 locks held by cat/4179:
#0: (&p->lock){+.+.+.}, at: [<c10a3884>] seq_read+0x25/0x315
#1: (&dev_priv->mm.active_list_lock){+.+...}, at: [<c119a854>]
i915_batchbuffer_info+0x2b/0x124
Pid: 4179, comm: cat Not tainted 2.6.32-rc5-git1 #2
Call Trace:
[<c104874f>] ? __debug_show_held_locks+0x1e/0x20
[<c1023fb0>] __might_sleep+0xf0/0xf7
[<c101c393>] kmap+0x17/0x58
[<c119a8d6>] i915_batchbuffer_info+0xad/0x124
[<c10a39bf>] seq_read+0x160/0x315
[<c108fb8c>] ? rw_verify_area+0x98/0xbb
[<c10a385f>] ? seq_read+0x0/0x315
[<c1090331>] vfs_read+0x75/0xa9
[<c10903f9>] sys_read+0x3b/0x5d
[<c1002a8f>] sysenter_do_call+0x12/0x36
The fix is relatively simple, use the atomic variants of kmap() that
avoid the potential sleep.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Miles Lane <miles.lane@gmail.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
According to the docs, the ringbuffer is not allowed to wrap in the middle
of an instruction.
G45 PRM, Vol 1b, p101:
While the “free space” wrap may allow commands to be wrapped around the
end of the Ring Buffer, the wrap should only occur between commands.
Padding (with NOP) may be required to follow this restriction.
Do as commanded.
[Having seen bug reports where there is evidence of split commands, but
apparently the GPU has continued on merrily before a bizarre and untimely
death, this may or may not fix a few random hangs.]
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
CC: Eric Anholt <eric@anholt.net>
Signed-off-by: Eric Anholt <eric@anholt.net>
Add a debugfs file to dump the entire register range. Here we
assume that reading write-only/reserved registers won't make the chip
angry. Seems to hold true, thankfully.
Signed-off-by: Ben Gamari <bgamari.foss@gmail.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
