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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: Andrea Righi <righi.andrea@gmail.com>
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andrea Righi 2008-07-26 15:22:27 -07:00 committed by Linus Torvalds
parent 6a9436d0c3
commit b2d002dba5
1 changed files with 21 additions and 33 deletions
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54
fs/proc/base.c
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@ -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 {
rchar = task->rchar;
wchar = task->wchar;
syscr = task->syscr;
syscw = task->syscw;
memcpy(&ioac, &task->ioac, sizeof(ioac));
if (whole) {
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 (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)