| From 2709add39074ff3e74acce05f3d0459d37fef34a Mon Sep 17 00:00:00 2001 |
| From: Neil Horman <nhorman@tuxdriver.com> |
| Date: Fri, 27 Apr 2012 10:11:48 +0000 |
| Subject: [PATCH] drop_monitor: fix sleeping in invalid context warning |
| |
| commit cde2e9a651b76d8db36ae94cd0febc82b637e5dd upstream. |
| |
| Eric Dumazet pointed out this warning in the drop_monitor protocol to me: |
| |
| [ 38.352571] BUG: sleeping function called from invalid context at kernel/mutex.c:85 |
| [ 38.352576] in_atomic(): 1, irqs_disabled(): 0, pid: 4415, name: dropwatch |
| [ 38.352580] Pid: 4415, comm: dropwatch Not tainted 3.4.0-rc2+ #71 |
| [ 38.352582] Call Trace: |
| [ 38.352592] [<ffffffff8153aaf0>] ? trace_napi_poll_hit+0xd0/0xd0 |
| [ 38.352599] [<ffffffff81063f2a>] __might_sleep+0xca/0xf0 |
| [ 38.352606] [<ffffffff81655b16>] mutex_lock+0x26/0x50 |
| [ 38.352610] [<ffffffff8153aaf0>] ? trace_napi_poll_hit+0xd0/0xd0 |
| [ 38.352616] [<ffffffff810b72d9>] tracepoint_probe_register+0x29/0x90 |
| [ 38.352621] [<ffffffff8153a585>] set_all_monitor_traces+0x105/0x170 |
| [ 38.352625] [<ffffffff8153a8ca>] net_dm_cmd_trace+0x2a/0x40 |
| [ 38.352630] [<ffffffff8154a81a>] genl_rcv_msg+0x21a/0x2b0 |
| [ 38.352636] [<ffffffff810f8029>] ? zone_statistics+0x99/0xc0 |
| [ 38.352640] [<ffffffff8154a600>] ? genl_rcv+0x30/0x30 |
| [ 38.352645] [<ffffffff8154a059>] netlink_rcv_skb+0xa9/0xd0 |
| [ 38.352649] [<ffffffff8154a5f0>] genl_rcv+0x20/0x30 |
| [ 38.352653] [<ffffffff81549a7e>] netlink_unicast+0x1ae/0x1f0 |
| [ 38.352658] [<ffffffff81549d76>] netlink_sendmsg+0x2b6/0x310 |
| [ 38.352663] [<ffffffff8150824f>] sock_sendmsg+0x10f/0x130 |
| [ 38.352668] [<ffffffff8150abe0>] ? move_addr_to_kernel+0x60/0xb0 |
| [ 38.352673] [<ffffffff81515f04>] ? verify_iovec+0x64/0xe0 |
| [ 38.352677] [<ffffffff81509c46>] __sys_sendmsg+0x386/0x390 |
| [ 38.352682] [<ffffffff810ffaf9>] ? handle_mm_fault+0x139/0x210 |
| [ 38.352687] [<ffffffff8165b5bc>] ? do_page_fault+0x1ec/0x4f0 |
| [ 38.352693] [<ffffffff8106ba4d>] ? set_next_entity+0x9d/0xb0 |
| [ 38.352699] [<ffffffff81310b49>] ? tty_ldisc_deref+0x9/0x10 |
| [ 38.352703] [<ffffffff8106d363>] ? pick_next_task_fair+0x63/0x140 |
| [ 38.352708] [<ffffffff8150b8d4>] sys_sendmsg+0x44/0x80 |
| [ 38.352713] [<ffffffff8165f8e2>] system_call_fastpath+0x16/0x1b |
| |
| It stems from holding a spinlock (trace_state_lock) while attempting to register |
| or unregister tracepoint hooks, making in_atomic() true in this context, leading |
| to the warning when the tracepoint calls might_sleep() while its taking a mutex. |
| Since we only use the trace_state_lock to prevent trace protocol state races, as |
| well as hardware stat list updates on an rcu write side, we can just convert the |
| spinlock to a mutex to avoid this problem. |
| |
| Signed-off-by: Neil Horman <nhorman@tuxdriver.com> |
| Reported-by: Eric Dumazet <eric.dumazet@gmail.com> |
| CC: David Miller <davem@davemloft.net> |
| Acked-by: Eric Dumazet <edumazet@google.com> |
| Signed-off-by: David S. Miller <davem@davemloft.net> |
| Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> |
| --- |
| net/core/drop_monitor.c | 14 +++++++------- |
| 1 file changed, 7 insertions(+), 7 deletions(-) |
| |
| diff --git a/net/core/drop_monitor.c b/net/core/drop_monitor.c |
| index cf208d8042b1..e596db9fefd0 100644 |
| --- a/net/core/drop_monitor.c |
| +++ b/net/core/drop_monitor.c |
| @@ -42,7 +42,7 @@ static void send_dm_alert(struct work_struct *unused); |
| * netlink alerts |
| */ |
| static int trace_state = TRACE_OFF; |
| -static DEFINE_SPINLOCK(trace_state_lock); |
| +static DEFINE_MUTEX(trace_state_mutex); |
| |
| struct per_cpu_dm_data { |
| struct work_struct dm_alert_work; |
| @@ -221,7 +221,7 @@ static int set_all_monitor_traces(int state) |
| struct dm_hw_stat_delta *new_stat = NULL; |
| struct dm_hw_stat_delta *temp; |
| |
| - spin_lock(&trace_state_lock); |
| + mutex_lock(&trace_state_mutex); |
| |
| switch (state) { |
| case TRACE_ON: |
| @@ -252,7 +252,7 @@ static int set_all_monitor_traces(int state) |
| if (!rc) |
| trace_state = state; |
| |
| - spin_unlock(&trace_state_lock); |
| + mutex_unlock(&trace_state_mutex); |
| |
| if (rc) |
| return -EINPROGRESS; |
| @@ -297,12 +297,12 @@ static int dropmon_net_event(struct notifier_block *ev_block, |
| |
| new_stat->dev = dev; |
| new_stat->last_rx = jiffies; |
| - spin_lock(&trace_state_lock); |
| + mutex_lock(&trace_state_mutex); |
| list_add_rcu(&new_stat->list, &hw_stats_list); |
| - spin_unlock(&trace_state_lock); |
| + mutex_unlock(&trace_state_mutex); |
| break; |
| case NETDEV_UNREGISTER: |
| - spin_lock(&trace_state_lock); |
| + mutex_lock(&trace_state_mutex); |
| list_for_each_entry_safe(new_stat, tmp, &hw_stats_list, list) { |
| if (new_stat->dev == dev) { |
| new_stat->dev = NULL; |
| @@ -313,7 +313,7 @@ static int dropmon_net_event(struct notifier_block *ev_block, |
| } |
| } |
| } |
| - spin_unlock(&trace_state_lock); |
| + mutex_unlock(&trace_state_mutex); |
| break; |
| } |
| out: |
| -- |
| 1.8.5.2 |
| |