Messages in this thread Patch in this message | | | From | Jiri Slaby <> | Subject | [PATCH 1/1] hw_breakpoints: fix locking in load_debug_registers | Date | Tue, 1 Sep 2009 00:01:38 +0200 |
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load_debug_registers is called with interrupts disabled from many contexts and causes a warning to be dropped, e.g.: ------------[ cut here ]------------ WARNING: at kernel/softirq.c:143 local_bh_enable_ip+0x75/0xa0() Hardware name: To Be Filled By O.E.M. Modules linked in: nfs lockd auth_rpcgss sunrpc ath5k ath Pid: 15083, comm: pm-suspend Tainted: G W 2.6.31-rc7-mm1_64 #687 Call Trace: [<ffffffff8103f6c8>] warn_slowpath_common+0x78/0xb0 [<ffffffff8103f70f>] warn_slowpath_null+0xf/0x20 [<ffffffff81045875>] local_bh_enable_ip+0x75/0xa0 [<ffffffff8142feff>] _spin_unlock_bh+0xf/0x20 [<ffffffff81089141>] load_debug_registers+0x51/0x60 [<ffffffff8134fa93>] restore_processor_state+0x1b3/0x240 [<ffffffff8119ba54>] acpi_suspend_enter+0x56/0xaf [<ffffffff8106e66d>] suspend_devices_and_enter+0x14d/0x1a0 [<ffffffff8106e79b>] enter_state+0xdb/0xf0 [<ffffffff8106ded1>] state_store+0x91/0x100 [<ffffffff8116ac77>] kobj_attr_store+0x17/0x20 [<ffffffff8111b2e0>] sysfs_write_file+0xe0/0x160 [<ffffffff810c33e8>] vfs_write+0xb8/0x1b0 [<ffffffff81432735>] ? do_page_fault+0x185/0x350 [<ffffffff810c3a4c>] sys_write+0x4c/0x80 [<ffffffff8100beeb>] system_call_fastpath+0x16/0x1b ---[ end trace fc3dd2304adb23aa ]---
Fix it by switching from spin_lock_bh to spin_lock_irqsave and removing nested local_irq_save.
Signed-off-by: Jiri Slaby <jirislaby@gmail.com> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: K.Prasad <prasad@linux.vnet.ibm.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> --- kernel/hw_breakpoint.c | 6 ++---- 1 files changed, 2 insertions(+), 4 deletions(-)
diff --git a/kernel/hw_breakpoint.c b/kernel/hw_breakpoint.c index c1f64e6..bc5368d 100644 --- a/kernel/hw_breakpoint.c +++ b/kernel/hw_breakpoint.c @@ -80,17 +80,15 @@ void load_debug_registers(void) unsigned long flags; struct task_struct *tsk = current; - spin_lock_bh(&hw_breakpoint_lock); + spin_lock_irqsave(&hw_breakpoint_lock, flags); /* Prevent IPIs for new kernel breakpoint updates */ - local_irq_save(flags); arch_update_kernel_hw_breakpoint(NULL); - local_irq_restore(flags); if (test_tsk_thread_flag(tsk, TIF_DEBUG)) arch_install_thread_hw_breakpoint(tsk); - spin_unlock_bh(&hw_breakpoint_lock); + spin_unlock_irqrestore(&hw_breakpoint_lock, flags); } /* -- 1.6.3.3
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