Commit 6c303d3a authored by Oleg Nesterov's avatar Oleg Nesterov
Browse files

tracing: let trace_signal_generate() report more info, kill overflow_fail/lose_info 



__send_signal()->trace_signal_generate() doesn't report enough info.
The users want to know was the signal actually delivered or not, and
they also need the shared/private info.

The patch moves trace_signal_generate() at the end of __send_signal()
and adds the 2 additional arguments.

This also allows us to kill trace_signal_overflow_fail/lose_info, we
can simply add the appropriate TRACE_SIGNAL_ "result" codes.

Reported-by: default avatarSeiji Aguchi <saguchi@redhat.com>
Reviewed-by: default avatarSeiji Aguchi <seiji.aguchi@hds.com>
Acked-by: default avatarSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
parent 09946950

include/trace/events/signal.h

+22 −63
Original line number Diff line number Diff line
@@ -23,11 +23,23 @@ 
		}						\

	} while (0)



#ifndef TRACE_HEADER_MULTI_READ

enum {

	TRACE_SIGNAL_DELIVERED,

	TRACE_SIGNAL_IGNORED,

	TRACE_SIGNAL_ALREADY_PENDING,

	TRACE_SIGNAL_OVERFLOW_FAIL,

	TRACE_SIGNAL_LOSE_INFO,

};

#endif



/**

 * signal_generate - called when a signal is generated

 * @sig: signal number

 * @info: pointer to struct siginfo

 * @task: pointer to struct task_struct

 * @group: shared or private

 * @result: TRACE_SIGNAL_*

 *

 * Current process sends a 'sig' signal to 'task' process with

 * 'info' siginfo. If 'info' is SEND_SIG_NOINFO or SEND_SIG_PRIV,
@@ -37,9 +49,10 @@ 
 */

TRACE_EVENT(signal_generate,



	TP_PROTO(int sig, struct siginfo *info, struct task_struct *task),

	TP_PROTO(int sig, struct siginfo *info, struct task_struct *task,

			int group, int result),



	TP_ARGS(sig, info, task),

	TP_ARGS(sig, info, task, group, result),



	TP_STRUCT__entry(

		__field(	int,	sig			)
@@ -47,6 +60,8 @@ TRACE_EVENT(signal_generate, 
		__field(	int,	code			)

		__array(	char,	comm,	TASK_COMM_LEN	)

		__field(	pid_t,	pid			)

		__field(	int,	group			)

		__field(	int,	result			)

	),



	TP_fast_assign(
@@ -54,11 +69,14 @@ TRACE_EVENT(signal_generate, 
		TP_STORE_SIGINFO(__entry, info);

		memcpy(__entry->comm, task->comm, TASK_COMM_LEN);

		__entry->pid	= task->pid;

		__entry->group	= group;

		__entry->result	= result;

	),



	TP_printk("sig=%d errno=%d code=%d comm=%s pid=%d",

	TP_printk("sig=%d errno=%d code=%d comm=%s pid=%d grp=%d res=%d",

		  __entry->sig, __entry->errno, __entry->code,

		  __entry->comm, __entry->pid)

		  __entry->comm, __entry->pid, __entry->group,

		  __entry->result)

);



/**
@@ -101,65 +119,6 @@ TRACE_EVENT(signal_deliver, 
		  __entry->sa_handler, __entry->sa_flags)

);



DECLARE_EVENT_CLASS(signal_queue_overflow,



	TP_PROTO(int sig, int group, struct siginfo *info),



	TP_ARGS(sig, group, info),



	TP_STRUCT__entry(

		__field(	int,	sig	)

		__field(	int,	group	)

		__field(	int,	errno	)

		__field(	int,	code	)

	),



	TP_fast_assign(

		__entry->sig	= sig;

		__entry->group	= group;

		TP_STORE_SIGINFO(__entry, info);

	),



	TP_printk("sig=%d group=%d errno=%d code=%d",

		  __entry->sig, __entry->group, __entry->errno, __entry->code)

);



/**

 * signal_overflow_fail - called when signal queue is overflow

 * @sig: signal number

 * @group: signal to process group or not (bool)

 * @info: pointer to struct siginfo

 *

 * Kernel fails to generate 'sig' signal with 'info' siginfo, because

 * siginfo queue is overflow, and the signal is dropped.

 * 'group' is not 0 if the signal will be sent to a process group.

 * 'sig' is always one of RT signals.

 */

DEFINE_EVENT(signal_queue_overflow, signal_overflow_fail,



	TP_PROTO(int sig, int group, struct siginfo *info),



	TP_ARGS(sig, group, info)

);



/**

 * signal_lose_info - called when siginfo is lost

 * @sig: signal number

 * @group: signal to process group or not (bool)

 * @info: pointer to struct siginfo

 *

 * Kernel generates 'sig' signal but loses 'info' siginfo, because siginfo

 * queue is overflow.

 * 'group' is not 0 if the signal will be sent to a process group.

 * 'sig' is always one of non-RT signals.

 */

DEFINE_EVENT(signal_queue_overflow, signal_lose_info,



	TP_PROTO(int sig, int group, struct siginfo *info),



	TP_ARGS(sig, group, info)

);



#endif /* _TRACE_SIGNAL_H */



/* This part must be outside protection */

kernel/signal.c

+14 −8
Original line number Diff line number Diff line
@@ -1054,13 +1054,13 @@ static int __send_signal(int sig, struct siginfo *info, struct task_struct *t, 
	struct sigpending *pending;

	struct sigqueue *q;

	int override_rlimit;



	trace_signal_generate(sig, info, t);

	int ret = 0, result;



	assert_spin_locked(&t->sighand->siglock);



	result = TRACE_SIGNAL_IGNORED;

	if (!prepare_signal(sig, t, from_ancestor_ns))

		return 0;

		goto ret;



	pending = group ? &t->signal->shared_pending : &t->pending;

	/*
@@ -1068,8 +1068,11 @@ static int __send_signal(int sig, struct siginfo *info, struct task_struct *t, 
	 * exactly one non-rt signal, so that we can get more

	 * detailed information about the cause of the signal.

	 */

	result = TRACE_SIGNAL_ALREADY_PENDING;

	if (legacy_queue(pending, sig))

		return 0;

		goto ret;



	result = TRACE_SIGNAL_DELIVERED;

	/*

	 * fast-pathed signals for kernel-internal things like SIGSTOP

	 * or SIGKILL.
@@ -1127,14 +1130,15 @@ static int __send_signal(int sig, struct siginfo *info, struct task_struct *t, 
			 * signal was rt and sent by user using something

			 * other than kill().

			 */

			trace_signal_overflow_fail(sig, group, info);

			return -EAGAIN;

			result = TRACE_SIGNAL_OVERFLOW_FAIL;

			ret = -EAGAIN;

			goto ret;

		} else {

			/*

			 * This is a silent loss of information.  We still

			 * send the signal, but the *info bits are lost.

			 */

			trace_signal_lose_info(sig, group, info);

			result = TRACE_SIGNAL_LOSE_INFO;

		}

	}
@@ -1142,7 +1146,9 @@ out_set: 
	signalfd_notify(t, sig);

	sigaddset(&pending->signal, sig);

	complete_signal(sig, t, group);

	return 0;

ret:

	trace_signal_generate(sig, info, t, group, result);

	return ret;

}



static int send_signal(int sig, struct siginfo *info, struct task_struct *t,

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