Re: [PATCH] blktrace: fix pdu_len when tracing packet command requests

[Li Zefan <lizf@cn.fujitsu.com>]

FUJITA Tomonori wrote:
> On Thu, 02 Apr 2009 10:17:26 +0800
> Li Zefan <lizf@cn.fujitsu.com> wrote:
> 
>> This bug has been here since 2.6.26.
>>
>> =======
>>
>> Since commit d7e3c3249ef23b4617393c69fe464765b4ff1645 ("block: add
>> large command support"), struct request->cmd has been changed from
>> unsinged char cmd[BLK_MAX_CDB] to unsigned char *cmd.
>>
>> Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
>> ---
>>  kernel/trace/blktrace.c |    2 +-
>>  1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
>> index fd1ff49..bafb8d3 100644
>> --- a/kernel/trace/blktrace.c
>> +++ b/kernel/trace/blktrace.c
>> @@ -642,7 +642,7 @@ static void blk_add_trace_rq(struct request_queue *q, struct request *rq,
>>  	if (blk_pc_request(rq)) {
>>  		what |= BLK_TC_ACT(BLK_TC_PC);
>>  		__blk_add_trace(bt, 0, rq->data_len, rw, what, rq->errors,
>> -				sizeof(rq->cmd), rq->cmd);
>> +				max_t(int, rq->cmd_len, BLK_MAX_CDB), rq->cmd);
>>  	} else  {
>>  		what |= BLK_TC_ACT(BLK_TC_FS);
>>  		__blk_add_trace(bt, rq->hard_sector, rq->hard_nr_sectors << 9,
>> -- 
> 
> The patch works however it would be cleaner to simply use cmd_len?
> 

Right! This looks better, thanks.

> diff --git a/block/blk-core.c b/block/blk-core.c
> index 996ed90..54765d7 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -132,6 +132,7 @@ void blk_rq_init(struct request_queue *q, struct request *rq)
>  	INIT_HLIST_NODE(&rq->hash);
>  	RB_CLEAR_NODE(&rq->rb_node);
>  	rq->cmd = rq->__cmd;
> +	rq->cmd_len = BLK_MAX_CDB;
>  	rq->tag = -1;
>  	rq->ref_count = 1;
>  }
> diff --git a/block/blktrace.c b/block/blktrace.c
> index 028120a..90b9ca4 100644
> --- a/block/blktrace.c
> +++ b/block/blktrace.c
> @@ -583,7 +583,7 @@ static void blk_add_trace_rq(struct request_queue *q, struct request *rq,
>  	if (blk_pc_request(rq)) {
>  		what |= BLK_TC_ACT(BLK_TC_PC);
>  		__blk_add_trace(bt, 0, rq->data_len, rw, what, rq->errors,
> -				sizeof(rq->cmd), rq->cmd);
> +				rq->cmd_len, rq->cmd);
>  	} else  {
>  		what |= BLK_TC_ACT(BLK_TC_FS);
>  		__blk_add_trace(bt, rq->hard_sector, rq->hard_nr_sectors << 9,
> 
>