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Commit b2d002db authored by Andrea Righi's avatar Andrea Righi Committed by Linus Torvalds
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task IO accounting: correctly account threads IO statistics 



Oleg Nesterov points out that we should check that the task is still alive
before we iterate over the threads.  This patch includes a fixup for this.

Also simplify do_io_accounting() implementation.

Signed-off-by: default avatarAndrea Righi <righi.andrea@gmail.com>
Signed-off-by: default avatarOleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 6a9436d0

fs/proc/base.c

+22 −34
Original line number Diff line number Diff line
@@ -2406,35 +2406,18 @@ static int do_io_accounting(struct task_struct *task, char *buffer, int whole) 
	u64 rchar, wchar, syscr, syscw;

	struct task_io_accounting ioac;



	if (!whole) {

	rchar = task->rchar;

	wchar = task->wchar;

	syscr = task->syscr;

	syscw = task->syscw;

	memcpy(&ioac, &task->ioac, sizeof(ioac));

	} else {

		unsigned long flags;

		struct task_struct *t = task;

		rchar = wchar = syscr = syscw = 0;

		memset(&ioac, 0, sizeof(ioac));



		rcu_read_lock();

		do {

			rchar += t->rchar;

			wchar += t->wchar;

			syscr += t->syscr;

			syscw += t->syscw;



			ioac.read_bytes += t->ioac.read_bytes;

			ioac.write_bytes += t->ioac.write_bytes;

			ioac.cancelled_write_bytes +=

					t->ioac.cancelled_write_bytes;

			t = next_thread(t);

		} while (t != task);

		rcu_read_unlock();

	if (whole) {

		unsigned long flags;



		if (lock_task_sighand(task, &flags)) {

			struct signal_struct *sig = task->signal;

			struct task_struct *t = task;



			rchar += sig->rchar;

			wchar += sig->wchar;
@@ -2445,11 +2428,20 @@ static int do_io_accounting(struct task_struct *task, char *buffer, int whole) 
			ioac.write_bytes += sig->ioac.write_bytes;

			ioac.cancelled_write_bytes +=

					sig->ioac.cancelled_write_bytes;

			while_each_thread(task, t) {

				rchar += t->rchar;

				wchar += t->wchar;

				syscr += t->syscr;

				syscw += t->syscw;



				ioac.read_bytes += t->ioac.read_bytes;

				ioac.write_bytes += t->ioac.write_bytes;

				ioac.cancelled_write_bytes +=

					t->ioac.cancelled_write_bytes;

			}

			unlock_task_sighand(task, &flags);

		}

	}



	return sprintf(buffer,

			"rchar: %llu\n"

			"wchar: %llu\n"
@@ -2458,13 +2450,9 @@ static int do_io_accounting(struct task_struct *task, char *buffer, int whole) 
			"read_bytes: %llu\n"

			"write_bytes: %llu\n"

			"cancelled_write_bytes: %llu\n",

			(unsigned long long)rchar,

			(unsigned long long)wchar,

			(unsigned long long)syscr,

			(unsigned long long)syscw,

			(unsigned long long)ioac.read_bytes,

			(unsigned long long)ioac.write_bytes,

			(unsigned long long)ioac.cancelled_write_bytes);

			rchar, wchar, syscr, syscw,

			ioac.read_bytes, ioac.write_bytes,

			ioac.cancelled_write_bytes);

}



static int proc_tid_io_accounting(struct task_struct *task, char *buffer)