MIPS: Alchemy: Fix dbdma ring destruction memory debugcheck.
authorManuel Lauss <manuel.lauss@googlemail.com>
Tue, 26 Jan 2010 19:39:33 +0000 (20:39 +0100)
committerRalf Baechle <ralf@linux-mips.org>
Mon, 1 Feb 2010 19:30:25 +0000 (20:30 +0100)
commit22f4bb68b301f4ab896e9b3b0431fdde962242d2
tree62767bbd1ad7d11dbbeea3482b7902f08ea178ce
parentbe8cde8b24c9dca1e54598690115eee5b1476519
MIPS: Alchemy: Fix dbdma ring destruction memory debugcheck.

DBDMA descriptors need to be located at 32-byte aligned addresses;
however kmalloc in conjunction with the SLAB allocator and
CONFIG_DEBUG_SLUB enabled doesn't deliver any.  The dbdma code works
around that by allocating a larger area and realigning the start
address within it.

When freeing a channel however this adjustment is not taken into
account which results in an oops:

Kernel bug detected[#1]:
[...]
Call Trace:
[<80186010>] cache_free_debugcheck+0x284/0x318
[<801869d8>] kfree+0xe8/0x2a0
[<8010b31c>] au1xxx_dbdma_chan_free+0x2c/0x7c
[<80388dc8>] au1x_pcm_dbdma_free+0x34/0x4c
[<80388fa8>] au1xpsc_pcm_close+0x28/0x38
[<80383cb8>] soc_codec_close+0x14c/0x1cc
[<8036dbb4>] snd_pcm_release_substream+0x60/0xac
[<8036dc40>] snd_pcm_release+0x40/0xa0
[<8018c7a8>] __fput+0x11c/0x228
[<80188f60>] filp_close+0x7c/0x98
[<80189018>] sys_close+0x9c/0xe4
[<801022a0>] stack_done+0x20/0x3c

Fix this by recording the address delivered by kmalloc() and using
it as parameter to kfree().

This fix is only necessary with the SLAB allocator and CONFIG_DEBUG_SLAB
enabled;  non-debug SLAB, SLUB do return nicely aligned addresses,
debug-enabled SLUB currently panics early in the boot process.

Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
To: Linux-MIPS <linux-mips@linux-mips.org>
Cc: Manuel Lauss <manuel.lauss@gmail.com>
Patchwork: http://patchwork.linux-mips.org/patch/878/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
arch/mips/alchemy/common/dbdma.c
arch/mips/include/asm/mach-au1x00/au1xxx_dbdma.h