lkml.org 
[lkml]   [2021]   [Apr]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH] block: Fix sys_ioprio_set(.which=IOPRIO_WHO_PGRP) task iteration

do_each_pid_thread() { } while_each_pid_thread() is a double loop and
thus break doesn't work as expected. Also, it should be used under
tasklist_lock because otherwise we can race against change_pid() for
PGID/SID.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
block/ioprio.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)

--- a/block/ioprio.c
+++ b/block/ioprio.c
@@ -119,11 +119,17 @@ SYSCALL_DEFINE3(ioprio_set, int, which,
pgrp = task_pgrp(current);
else
pgrp = find_vpid(who);
+
+ read_lock(&tasklist_lock);
do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
ret = set_task_ioprio(p, ioprio);
- if (ret)
- break;
+ if (ret) {
+ read_unlock(&tasklist_lock);
+ goto out;
+ }
} while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
+ read_unlock(&tasklist_lock);
+
break;
case IOPRIO_WHO_USER:
uid = make_kuid(current_user_ns(), who);
@@ -153,6 +159,7 @@ SYSCALL_DEFINE3(ioprio_set, int, which,
ret = -EINVAL;
}

+out:
rcu_read_unlock();
return ret;
}
\
 
 \ /
  Last update: 2021-04-08 18:47    [W:0.034 / U:0.012 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site