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SubjectRe: [PATCH] mmc: Provide tracepoints for request processing
From
On 24 March 2016 at 23:13, Steven Rostedt <rostedt@goodmis.org> wrote:
> On Thu, 24 Mar 2016 19:54:08 +0800
> Baolin Wang <baolin.wang@linaro.org> wrote:
>
>
>> +++ b/include/trace/events/mmc.h
>> @@ -0,0 +1,188 @@
>> +#undef TRACE_SYSTEM
>> +#define TRACE_SYSTEM mmc
>> +
>> +#if !defined(_TRACE_MMC_H) || defined(TRACE_HEADER_MULTI_READ)
>> +#define _TRACE_MMC_H
>> +
>> +#include <linux/blkdev.h>
>> +#include <linux/mmc/core.h>
>> +#include <linux/mmc/host.h>
>> +#include <linux/tracepoint.h>
>> +
>> +DECLARE_EVENT_CLASS(mmc_request,
>> +
>> + TP_PROTO(struct request *rq),
>> +
>> + TP_ARGS(rq),
>> +
>> + TP_STRUCT__entry(
>> + __field(sector_t, sector)
>> + __field(unsigned int, data_len)
>> + __field(int, cmd_dir)
>> + __field(struct request *, rq)
>> + ),
>> +
>> + TP_fast_assign(
>> + __entry->sector = blk_rq_pos(rq);
>> + __entry->data_len = blk_rq_bytes(rq);
>> + __entry->cmd_dir = rq_data_dir(rq);
>> + __entry->rq = rq;
>> + ),
>> +
>> + TP_printk("struct request[%p]:sector=%lu rw=%d len=%u",
>> + (struct request *)__entry->rq,
>> + (unsigned long)__entry->sector,
>> + (int)__entry->cmd_dir,
>> + (unsigned int)__entry->data_len)
>
> Why the typecasts? __entry->rq is already of the type "struct request *"
> as you declared it in the TP_STRUCT__entry(). Same for the other fields.

Oh, I'll remove all the typecasts. Thanks.

>
>
>> +);
>> +
>> +DEFINE_EVENT(mmc_request, mmc_queue_fetch,
>> +
>> + TP_PROTO(struct request *rq),
>> +
>> + TP_ARGS(rq)
>> +
>> +);
>> +
>> +DEFINE_EVENT(mmc_request, mmc_block_packed_req,
>> +
>> + TP_PROTO(struct request *rq),
>> +
>> + TP_ARGS(rq)
>> +
>> +);
>> +
>> +DEFINE_EVENT(mmc_request, mmc_block_req_done,
>> +
>> + TP_PROTO(struct request *rq),
>> +
>> + TP_ARGS(rq)
>> +
>> +);
>> +
>> +TRACE_EVENT(mmc_request_start,
>> +
>> + TP_PROTO(struct mmc_host *host, struct mmc_request *mrq),
>> +
>> + TP_ARGS(host, mrq),
>> +
>> + TP_STRUCT__entry(
>> + __field(u32, cmd_opcode)
>> + __field(u32, cmd_arg)
>> + __field(unsigned int, cmd_flags)
>> + __field(u32, stop_opcode)
>> + __field(u32, stop_arg)
>> + __field(unsigned int, stop_flags)
>> + __field(u32, sbc_opcode)
>> + __field(u32, sbc_arg)
>> + __field(unsigned int, sbc_flags)
>> + __field(unsigned int, blocks)
>> + __field(unsigned int, blksz)
>> + __field(unsigned int, data_flags)
>> + __field(struct mmc_request *, mrq)
>> + __field(struct mmc_host *, host)
>> + ),
>> +
>> + TP_fast_assign(
>> + __entry->cmd_opcode = mrq->cmd->opcode;
>> + __entry->cmd_arg = mrq->cmd->arg;
>> + __entry->cmd_flags = mrq->cmd->flags;
>> + __entry->stop_opcode = mrq->stop ? mrq->stop->opcode : 0;
>> + __entry->stop_arg = mrq->stop ? mrq->stop->arg : 0;
>> + __entry->stop_flags = mrq->stop ? mrq->stop->flags : 0;
>> + __entry->sbc_opcode = mrq->sbc ? mrq->sbc->opcode : 0;
>> + __entry->sbc_arg = mrq->sbc ? mrq->sbc->arg : 0;
>> + __entry->sbc_flags = mrq->sbc ? mrq->sbc->flags : 0;
>> + __entry->blksz = mrq->data ? mrq->data->blksz : 0;
>> + __entry->blocks = mrq->data ? mrq->data->blocks : 0;
>> + __entry->data_flags = mrq->data ? mrq->data->flags : 0;
>> + __entry->mrq = mrq;
>> + __entry->host = host;
>> + ),
>> +
>> + TP_printk("%s: start struct mmc_request[%p]: "
>> + "cmd_opcode=%u cmd_arg=0x%x cmd_flags=0x%x "
>> + "stop_opcode=%u stop_arg=0x%x stop_flags=0x%x "
>> + "sbc_opcode=%u sbc_arg=0x%x sbc_flags=0x%x "
>> + "blocks=%u blksz=%u data_flags=0x%x",
>> + mmc_hostname((struct mmc_host *)__entry->host),
>
> Is this safe? I see mmc_hostname() defined as:
>
> dev_name(&(x)->class_dev)
>
> Which would be here:
>
> dev_name(&(__entry->host)->class_dev)
>
> How what happens if ater you trace a host, you free it? Then the old
> pointer will still be in the buffer. If the user reads the trace data
> and this is called, then __entry->host will be pointing to freed data,
> and the dereference could cause a system crash.

Sorry, I missed that, you are right. I'll fix that in next version.
Thanks for your good comments.

>
>
>> + (struct mmc_request *)__entry->mrq,
>> + (u32)__entry->cmd_opcode, (u32)__entry->cmd_arg,
>> + (unsigned int)__entry->cmd_flags,
>> + (u32)__entry->stop_opcode, (u32)__entry->stop_arg,
>> + (unsigned int)__entry->stop_flags,
>> + (u32)__entry->sbc_opcode, (u32)__entry->sbc_arg,
>> + (unsigned int)__entry->sbc_flags,
>> + (unsigned int)__entry->blocks,
>> + (unsigned int)__entry->blksz,
>> + (unsigned int)__entry->data_flags)
>> +);
>> +
>> +TRACE_EVENT(mmc_request_done,
>> +
>> + TP_PROTO(struct mmc_host *host, struct mmc_request *mrq),
>> +
>> + TP_ARGS(host, mrq),
>> +
>> + TP_STRUCT__entry(
>> + __field(u32, cmd_opcode)
>> + __field(int, cmd_err)
>> + __array(u32, cmd_resp, 4)
>> + __field(u32, stop_opcode)
>> + __field(int, stop_err)
>> + __array(u32, stop_resp, 4)
>> + __field(u32, sbc_opcode)
>> + __field(int, sbc_err)
>> + __array(u32, sbc_resp, 4)
>> + __field(unsigned int, bytes_xfered)
>> + __field(int, data_err)
>> + __field(struct mmc_request *, mrq)
>> + __field(struct mmc_host *, host)
>> + ),
>> +
>> + TP_fast_assign(
>> + __entry->cmd_opcode = mrq->cmd->opcode;
>> + __entry->cmd_err = mrq->cmd->error;
>> + memcpy(__entry->cmd_resp, mrq->cmd->resp, 4);
>> + __entry->stop_opcode = mrq->stop ? mrq->stop->opcode : 0;
>> + __entry->stop_err = mrq->stop ? mrq->stop->error : 0;
>> + __entry->stop_resp[0] = mrq->stop ? mrq->stop->resp[0] : 0;
>> + __entry->stop_resp[1] = mrq->stop ? mrq->stop->resp[1] : 0;
>> + __entry->stop_resp[2] = mrq->stop ? mrq->stop->resp[2] : 0;
>> + __entry->stop_resp[3] = mrq->stop ? mrq->stop->resp[3] : 0;
>> + __entry->sbc_opcode = mrq->sbc ? mrq->sbc->opcode : 0;
>> + __entry->sbc_err = mrq->sbc ? mrq->sbc->error : 0;
>> + __entry->sbc_resp[0] = mrq->sbc ? mrq->sbc->resp[0] : 0;
>> + __entry->sbc_resp[1] = mrq->sbc ? mrq->sbc->resp[1] : 0;
>> + __entry->sbc_resp[2] = mrq->sbc ? mrq->sbc->resp[2] : 0;
>> + __entry->sbc_resp[3] = mrq->sbc ? mrq->sbc->resp[3] : 0;
>> + __entry->bytes_xfered = mrq->data ? mrq->data->bytes_xfered : 0;
>> + __entry->data_err = mrq->data ? mrq->data->error : 0;
>> + __entry->host = host;
>> + __entry->mrq = mrq;
>> + ),
>> +
>> + TP_printk("%s: end struct mmc_request[%p]: "
>> + "cmd_opcode=%u cmd_err=%d cmd_resp=0x%x 0x%x 0x%x 0x%x "
>> + "stop_opcode=%u stop_err=%d stop_resp=0x%x 0x%x 0x%x 0x%x "
>> + "sbc_opcode=%u sbc_err=%d sbc_resp=0x%x 0x%x 0x%x 0x%x "
>> + "bytes_xfered=%u data_err=%d",
>> + mmc_hostname((struct mmc_host *)__entry->host),
>
> Same here, and please get rid of all the redundant typecasts.

OK.

>
> -- Steve
>
>> + (struct mmc_request *)__entry->mrq,
>> + (u32)__entry->cmd_opcode, (int)__entry->cmd_err,
>> + (u32)__entry->cmd_resp[0], (u32)__entry->cmd_resp[1],
>> + (u32)__entry->cmd_resp[2], (u32)__entry->cmd_resp[3],
>> + (u32)__entry->stop_opcode, (int)__entry->stop_err,
>> + (u32)__entry->stop_resp[0], (u32)__entry->stop_resp[1],
>> + (u32)__entry->stop_resp[2], (u32)__entry->stop_resp[3],
>> + (u32)__entry->sbc_opcode, (int)__entry->sbc_err,
>> + (u32)__entry->sbc_resp[0], (u32)__entry->sbc_resp[1],
>> + (u32)__entry->sbc_resp[2], (u32)__entry->sbc_resp[3],
>> + (unsigned int)__entry->bytes_xfered,
>> + (int)__entry->data_err)
>> +);
>> +
>> +#endif /* _TRACE_MMC_H */
>> +
>> +/* This part must be outside protection */
>> +#include <trace/define_trace.h>
>



--
Baolin.wang
Best Regards

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