| From: Mike Galbraith <umgwanakikbuti@gmail.com> |
| Date: Sun, 16 Oct 2016 05:11:54 +0200 |
| Subject: [PATCH] connector/cn_proc: Protect send_msg() with a local lock |
| on RT |
| |
| |BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:931 |
| |in_atomic(): 1, irqs_disabled(): 0, pid: 31807, name: sleep |
| |Preemption disabled at:[<ffffffff8148019b>] proc_exit_connector+0xbb/0x140 |
| | |
| |CPU: 4 PID: 31807 Comm: sleep Tainted: G W E 4.8.0-rt11-rt #106 |
| |Call Trace: |
| | [<ffffffff813436cd>] dump_stack+0x65/0x88 |
| | [<ffffffff8109c425>] ___might_sleep+0xf5/0x180 |
| | [<ffffffff816406b0>] __rt_spin_lock+0x20/0x50 |
| | [<ffffffff81640978>] rt_read_lock+0x28/0x30 |
| | [<ffffffff8156e209>] netlink_broadcast_filtered+0x49/0x3f0 |
| | [<ffffffff81522621>] ? __kmalloc_reserve.isra.33+0x31/0x90 |
| | [<ffffffff8156e5cd>] netlink_broadcast+0x1d/0x20 |
| | [<ffffffff8147f57a>] cn_netlink_send_mult+0x19a/0x1f0 |
| | [<ffffffff8147f5eb>] cn_netlink_send+0x1b/0x20 |
| | [<ffffffff814801d8>] proc_exit_connector+0xf8/0x140 |
| | [<ffffffff81077f71>] do_exit+0x5d1/0xba0 |
| | [<ffffffff810785cc>] do_group_exit+0x4c/0xc0 |
| | [<ffffffff81078654>] SyS_exit_group+0x14/0x20 |
| | [<ffffffff81640a72>] entry_SYSCALL_64_fastpath+0x1a/0xa4 |
| |
| Since ab8ed951080e ("connector: fix out-of-order cn_proc netlink message |
| delivery") which is v4.7-rc6. |
| |
| Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com> |
| Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> |
| --- |
| drivers/connector/cn_proc.c | 6 ++++-- |
| 1 file changed, 4 insertions(+), 2 deletions(-) |
| |
| --- a/drivers/connector/cn_proc.c |
| +++ b/drivers/connector/cn_proc.c |
| @@ -32,6 +32,7 @@ |
| #include <linux/pid_namespace.h> |
| |
| #include <linux/cn_proc.h> |
| +#include <linux/locallock.h> |
| |
| /* |
| * Size of a cn_msg followed by a proc_event structure. Since the |
| @@ -54,10 +55,11 @@ static struct cb_id cn_proc_event_id = { |
| |
| /* proc_event_counts is used as the sequence number of the netlink message */ |
| static DEFINE_PER_CPU(__u32, proc_event_counts) = { 0 }; |
| +static DEFINE_LOCAL_IRQ_LOCK(send_msg_lock); |
| |
| static inline void send_msg(struct cn_msg *msg) |
| { |
| - preempt_disable(); |
| + local_lock(send_msg_lock); |
| |
| msg->seq = __this_cpu_inc_return(proc_event_counts) - 1; |
| ((struct proc_event *)msg->data)->cpu = smp_processor_id(); |
| @@ -70,7 +72,7 @@ static inline void send_msg(struct cn_ms |
| */ |
| cn_netlink_send(msg, 0, CN_IDX_PROC, GFP_NOWAIT); |
| |
| - preempt_enable(); |
| + local_unlock(send_msg_lock); |
| } |
| |
| void proc_fork_connector(struct task_struct *task) |