Re: [PATCH] fs: jffs2: Add setup code for spi nor flash.

[sourav <sourav.poddar@ti.com>]

On Thursday 09 January 2014 09:46 PM, Brian Norris wrote:
> On Mon, Dec 09, 2013 at 10:44:35AM +0530, Sourav Poddar wrote:
>> Flash need to be setup, while using it for Jffs2 filesystem.
>> The setup code checks was not present for serial flash like
>> m25p80. As a result of which, internal pointers/buffers are in unknown
>> state. This leads to
>> a. dumps like below[1] while mounting a jffs2 filesystem.
>> b. Hang while doing a mount second time.
>>
>> [1]:
>> root@am437x-evm:~# sync
>> [   84.112640] INFO: trying to register non-static key.
>> [   84.117553] the code is fine but needs lockdep annotation.
>> [   84.122985] turning off the locking correctness validator.
>> [   84.128417] CPU: 0 PID: 1289 Comm: sync Not tainted 3.12.0-67367-g2d1978c-dirty #18
>> [   84.136016] [<c001bcb8>] (unwind_backtrace+0x0/0xf0) from [<c0017dd0>] (show_stack+0x10/0x14)
>> [   84.144439] [<c0017dd0>] (show_stack+0x10/0x14) from [<c05a69c8>] (dump_stack+0x78/0x94)
>> [   84.152465] [<c05a69c8>] (dump_stack+0x78/0x94) from [<c009e2e0>] (__lock_acquire+0x1788/0x1b8c)
>> [   84.161132] [<c009e2e0>] (__lock_acquire+0x1788/0x1b8c) from [<c009ec30>] (lock_acquire+0x9c/0x104)
>> [   84.170104] [<c009ec30>] (lock_acquire+0x9c/0x104) from [<c005ede8>] (flush_work+0x38/0x78)
>> [   84.178375] [<c005ede8>] (flush_work+0x38/0x78) from [<c005eef0>] (__cancel_work_timer+0x84/0x124)
>> [   84.187225] [<c005eef0>] (__cancel_work_timer+0x84/0x124) from [<c024c1d4>] (jffs2_sync_fs+0x14/0x38)
>> [   84.196380] [<c024c1d4>] (jffs2_sync_fs+0x14/0x38) from [<c013c138>] (sync_fs_one_sb+0x28/0x2c)
>> [   84.204986] [<c013c138>] (sync_fs_one_sb+0x28/0x2c) from [<c0115360>] (iterate_supers+0xb0/0xd8)
>> [   84.213684] [<c0115360>] (iterate_supers+0xb0/0xd8) from [<c013c228>] (sys_sync+0x3c/0x98)
>> [   84.221862] [<c013c228>] (sys_sync+0x3c/0x98) from [<c0013dc0>] (ret_fast_syscall+0x0/0x48)
>>
>> The patch fixes the above two issue.
> Are you sure this symptom is caused by the cause you note? It doesn't
> quite seem obvious to me, but I suppose uninitialized buffers/pointers
> can cause a wide range of issues.
Yes, i tried this few times with and w/o this patch and see this. Code
tracing points to this particular area where buffer remain uninitiatised.
>
>> Signed-off-by: Sourav Poddar<sourav.poddar@ti.com>
>> Signed-off-by: George Cherian<george.cherian@ti.com>
>> ---
>>   fs/jffs2/fs.c       |    7 +++++++
>>   fs/jffs2/os-linux.h |    2 ++
>>   2 files changed, 9 insertions(+), 0 deletions(-)
>>
>> diff --git a/fs/jffs2/fs.c b/fs/jffs2/fs.c
>> index fe3c052..02003f0 100644
>> --- a/fs/jffs2/fs.c
>> +++ b/fs/jffs2/fs.c
>> @@ -725,6 +725,13 @@ static int jffs2_flash_setup(struct jffs2_sb_info *c) {
>>   			return ret;
>>   	}
>>
>> +	/* m25p80 spi flash */
>> +	if (jffs2_nor_spi_wbuf_flash(c)) {
>> +		ret = jffs2_nor_wbuf_flash_setup(c);
> If you add this, you need to add the corresponding cleanup
> (jffs2_nor_wbuf_flash_cleanup()) in jffs2_flash_cleanup().
Ok. will do.
>
>> +		if (ret)
>> +			return ret;
>> +	}
>> +
>>   	/* and an UBI volume */
>>   	if (jffs2_ubivol(c)) {
>>   		ret = jffs2_ubivol_setup(c);
>> diff --git a/fs/jffs2/os-linux.h b/fs/jffs2/os-linux.h
>> index d200a9b..09ba999 100644
>> --- a/fs/jffs2/os-linux.h
>> +++ b/fs/jffs2/os-linux.h
>> @@ -134,6 +134,8 @@ int jffs2_ubivol_setup(struct jffs2_sb_info *c);
>>   void jffs2_ubivol_cleanup(struct jffs2_sb_info *c);
>>
>>   #define jffs2_nor_wbuf_flash(c) (c->mtd->type == MTD_NORFLASH&&  ! (c->mtd->flags&  MTD_BIT_WRITEABLE))
>> +#define jffs2_nor_spi_wbuf_flash(c) \
>> +	(c->mtd->type == MTD_NORFLASH&&  (c->mtd->flags&  MTD_CAP_NORFLASH))
> How is this check distinct from the existing jffs2_nor_wbuf_flash()
> check? Is m25p80 bit-writeable? IOW, are you sure that the following
> code doesn't alread cover m25p80?
Yes, m25p80 supports CAP_NORFLASH which is WRITEABLE | BIT_WRITEABLE,
while the below Intel code will make the condition false by ! and we spi 
flash
setup will not take place. Hence, we need a new #define for spi flash.

> 	/* and Intel "Sibley" flash */
> 		if (jffs2_nor_wbuf_flash(c)) {
> 		...
>
>>   int jffs2_nor_wbuf_flash_setup(struct jffs2_sb_info *c);
>>   void jffs2_nor_wbuf_flash_cleanup(struct jffs2_sb_info *c);
>>   void jffs2_dirty_trigger(struct jffs2_sb_info *c);
> Brian