Re: [PATCH v2 1/3] io_uring: Add to traces the req pointer when available

[Pavel Begunkov <asml.silence@gmail.com>]

On 5/31/21 7:36 AM, Olivier Langlois wrote:
> The req pointer uniquely identify a specific request.
> Having it in traces can provide valuable insights that is not possible
> to have if the calling process is reusing the same user_data value.

Patchset are usually accompanied with a cover letter. Also, there is
something wrong as b4 refuses to find the patch. Anyway...

Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>

> Signed-off-by: Olivier Langlois <olivier@trillion01.com>
> ---
>  fs/io_uring.c                   | 11 ++---
>  include/trace/events/io_uring.h | 71 ++++++++++++++++++++++++---------
>  2 files changed, 59 insertions(+), 23 deletions(-)
> 
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index 903458afd56c..0737b0e76b91 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -5059,7 +5059,7 @@ static void io_async_task_func(struct callback_head *cb)
>  	struct async_poll *apoll = req->apoll;
>  	struct io_ring_ctx *ctx = req->ctx;
>  
> -	trace_io_uring_task_run(req->ctx, req->opcode, req->user_data);
> +	trace_io_uring_task_run(req->ctx, req, req->opcode, req->user_data);
>  
>  	if (io_poll_rewait(req, &apoll->poll)) {
>  		spin_unlock_irq(&ctx->completion_lock);
> @@ -5192,8 +5192,8 @@ static bool io_arm_poll_handler(struct io_kiocb *req)
>  		return false;
>  	}
>  	spin_unlock_irq(&ctx->completion_lock);
> -	trace_io_uring_poll_arm(ctx, req->opcode, req->user_data, mask,
> -					apoll->poll.events);
> +	trace_io_uring_poll_arm(ctx, req, req->opcode, req->user_data,
> +				mask, apoll->poll.events);
>  	return true;
>  }
>  
> @@ -6578,8 +6578,9 @@ static int io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
>  		goto fail_req;
>  
>  	/* don't need @sqe from now on */
> -	trace_io_uring_submit_sqe(ctx, req->opcode, req->user_data,
> -				true, ctx->flags & IORING_SETUP_SQPOLL);
> +	trace_io_uring_submit_sqe(ctx, req, req->opcode, req->user_data,
> +				  req->flags, true,
> +				  ctx->flags & IORING_SETUP_SQPOLL);
>  
>  	/*
>  	 * If we already have a head request, queue this one for async
> diff --git a/include/trace/events/io_uring.h b/include/trace/events/io_uring.h
> index abb8b24744fd..12addad1f837 100644
> --- a/include/trace/events/io_uring.h
> +++ b/include/trace/events/io_uring.h
> @@ -323,8 +323,10 @@ TRACE_EVENT(io_uring_complete,
>   * io_uring_submit_sqe - called before submitting one SQE
>   *
>   * @ctx:		pointer to a ring context structure
> + * @req:		pointer to a submitted request
>   * @opcode:		opcode of request
>   * @user_data:		user data associated with the request
> + * @flags		request flags
>   * @force_nonblock:	whether a context blocking or not
>   * @sq_thread:		true if sq_thread has submitted this SQE
>   *
> @@ -333,41 +335,60 @@ TRACE_EVENT(io_uring_complete,
>   */
>  TRACE_EVENT(io_uring_submit_sqe,
>  
> -	TP_PROTO(void *ctx, u8 opcode, u64 user_data, bool force_nonblock,
> -		 bool sq_thread),
> +	TP_PROTO(void *ctx, void *req, u8 opcode, u64 user_data, u32 flags,
> +		 bool force_nonblock, bool sq_thread),
>  
> -	TP_ARGS(ctx, opcode, user_data, force_nonblock, sq_thread),
> +	TP_ARGS(ctx, req, opcode, user_data, flags, force_nonblock, sq_thread),
>  
>  	TP_STRUCT__entry (
>  		__field(  void *,	ctx		)
> +		__field(  void *,	req		)
>  		__field(  u8,		opcode		)
>  		__field(  u64,		user_data	)
> +		__field(  u32,		flags		)
>  		__field(  bool,		force_nonblock	)
>  		__field(  bool,		sq_thread	)
>  	),
>  
>  	TP_fast_assign(
>  		__entry->ctx		= ctx;
> +		__entry->req		= req;
>  		__entry->opcode		= opcode;
>  		__entry->user_data	= user_data;
> +		__entry->flags		= flags;
>  		__entry->force_nonblock	= force_nonblock;
>  		__entry->sq_thread	= sq_thread;
>  	),
>  
> -	TP_printk("ring %p, op %d, data 0x%llx, non block %d, sq_thread %d",
> -			  __entry->ctx, __entry->opcode,
> -			  (unsigned long long) __entry->user_data,
> -			  __entry->force_nonblock, __entry->sq_thread)
> +	TP_printk("ring %p, req %p, op %d, data 0x%llx, flags %u, "
> +		  "non block %d, sq_thread %d", __entry->ctx, __entry->req,
> +		  __entry->opcode, (unsigned long long)__entry->user_data,
> +		  __entry->flags, __entry->force_nonblock, __entry->sq_thread)
>  );
>  
> +/*
> + * io_uring_poll_arm - called after arming a poll wait if successful
> + *
> + * @ctx:		pointer to a ring context structure
> + * @req:		pointer to the armed request
> + * @opcode:		opcode of request
> + * @user_data:		user data associated with the request
> + * @mask:		request poll events mask
> + * @events:		registered events of interest
> + *
> + * Allows to track which fds are waiting for and what are the events of
> + * interest.
> + */
>  TRACE_EVENT(io_uring_poll_arm,
>  
> -	TP_PROTO(void *ctx, u8 opcode, u64 user_data, int mask, int events),
> +	TP_PROTO(void *ctx, void *req, u8 opcode, u64 user_data,
> +		 int mask, int events),
>  
> -	TP_ARGS(ctx, opcode, user_data, mask, events),
> +	TP_ARGS(ctx, req, opcode, user_data, mask, events),
>  
>  	TP_STRUCT__entry (
>  		__field(  void *,	ctx		)
> +		__field(  void *,	req		)
>  		__field(  u8,		opcode		)
>  		__field(  u64,		user_data	)
>  		__field(  int,		mask		)
> @@ -376,16 +397,17 @@ TRACE_EVENT(io_uring_poll_arm,
>  
>  	TP_fast_assign(
>  		__entry->ctx		= ctx;
> +		__entry->req		= req;
>  		__entry->opcode		= opcode;
>  		__entry->user_data	= user_data;
>  		__entry->mask		= mask;
>  		__entry->events		= events;
>  	),
>  
> -	TP_printk("ring %p, op %d, data 0x%llx, mask 0x%x, events 0x%x",
> -			  __entry->ctx, __entry->opcode,
> -			  (unsigned long long) __entry->user_data,
> -			  __entry->mask, __entry->events)
> +	TP_printk("ring %p, req %p, op %d, data 0x%llx, mask 0x%x, events 0x%x",
> +		  __entry->ctx, __entry->req, __entry->opcode,
> +		  (unsigned long long) __entry->user_data,
> +		  __entry->mask, __entry->events)
>  );
>  
>  TRACE_EVENT(io_uring_poll_wake,
> @@ -440,27 +462,40 @@ TRACE_EVENT(io_uring_task_add,
>  			  __entry->mask)
>  );
>  
> +/*
> + * io_uring_task_run - called when task_work_run() executes the poll events
> + *                     notification callbacks
> + *
> + * @ctx:		pointer to a ring context structure
> + * @req:		pointer to the armed request
> + * @opcode:		opcode of request
> + * @user_data:		user data associated with the request
> + *
> + * Allows to track when notified poll events are processed
> + */
>  TRACE_EVENT(io_uring_task_run,
>  
> -	TP_PROTO(void *ctx, u8 opcode, u64 user_data),
> +	TP_PROTO(void *ctx, void *req, u8 opcode, u64 user_data),
>  
> -	TP_ARGS(ctx, opcode, user_data),
> +	TP_ARGS(ctx, req, opcode, user_data),
>  
>  	TP_STRUCT__entry (
>  		__field(  void *,	ctx		)
> +		__field(  void *,	req		)
>  		__field(  u8,		opcode		)
>  		__field(  u64,		user_data	)
>  	),
>  
>  	TP_fast_assign(
>  		__entry->ctx		= ctx;
> +		__entry->req		= req;
>  		__entry->opcode		= opcode;
>  		__entry->user_data	= user_data;
>  	),
>  
> -	TP_printk("ring %p, op %d, data 0x%llx",
> -			  __entry->ctx, __entry->opcode,
> -			  (unsigned long long) __entry->user_data)
> +	TP_printk("ring %p, req %p, op %d, data 0x%llx",
> +		  __entry->ctx, __entry->req, __entry->opcode,
> +		  (unsigned long long) __entry->user_data)
>  );
>  
>  #endif /* _TRACE_IO_URING_H */
> 

-- 
Pavel Begunkov