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net: Add rtnl_lock_killable() 

rtnl_lock() is widely used mutex in kernel. Some of kernel code
does memory allocations under it. In case of memory deficit this
may invoke OOM killer, but the problem is a killed task can't
exit if it's waiting for the mutex. This may be a reason of deadlock
and panic.

This patch adds a new primitive, which responds on SIGKILL, and
it allows to use it in the places, where we don't want to sleep
forever.

Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Kirill Tkhai 2018-03-14 22:17:20 +03:00 committed by David S. Miller
parent 320bd6de79
commit 79ffdfc652
2 changed files with 7 additions and 0 deletions
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1
include/linux/rtnetlink.h
View File

@ -33,6 +33,7 @@ extern void rtnl_lock(void);
extern void rtnl_unlock(void);
extern int rtnl_trylock(void);
extern int rtnl_is_locked(void);
extern int rtnl_lock_killable(void);
extern wait_queue_head_t netdev_unregistering_wq;
extern struct rw_semaphore net_sem;

6
net/core/rtnetlink.c
View File

@ -75,6 +75,12 @@ void rtnl_lock(void)
}
EXPORT_SYMBOL(rtnl_lock);
int rtnl_lock_killable(void)
{
return mutex_lock_killable(&rtnl_mutex);
}
EXPORT_SYMBOL(rtnl_lock_killable);
static struct sk_buff *defer_kfree_skb_list;
void rtnl_kfree_skbs(struct sk_buff *head, struct sk_buff *tail)
{