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ARM/hw_breakpoint: Use cpuhp_setup_state_cpuslocked()

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arch_hw_breakpoint_init() holds get_online_cpus() while registerring the
hotplug callbacks.

cpuhp_setup_state() invokes get_online_cpus() as well. This is correct, but
prevents the conversion of the hotplug locking to a percpu rwsem.

Use cpuhp_setup_state_cpuslocked() to avoid the nested call. Convert
*_online_cpus() to the new interfaces while at it.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/20170524081548.170940729@linutronix.de
This commit is contained in:
Sebastian Andrzej Siewior 2017-05-24 10:15:25 +02:00 committed by Thomas Gleixner
parent 04b247c2eb
commit fe2a5cd8aa
1 changed files with 6 additions and 5 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

11
arch/arm/kernel/hw_breakpoint.c
View file

@ -1090,7 +1090,7 @@ static int __init arch_hw_breakpoint_init(void)
* driven low on this core and there isn't an architected way to
* determine that.
*/
get_online_cpus();
cpus_read_lock();
register_undef_hook(&debug_reg_hook);
/*
@ -1098,15 +1098,16 @@ static int __init arch_hw_breakpoint_init(void)
* assume that a halting debugger will leave the world in a nice state
* for us.
*/
ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "arm/hw_breakpoint:online",
dbg_reset_online, NULL);
ret = cpuhp_setup_state_cpuslocked(CPUHP_AP_ONLINE_DYN,
"arm/hw_breakpoint:online",
dbg_reset_online, NULL);
unregister_undef_hook(&debug_reg_hook);
if (WARN_ON(ret < 0) || !cpumask_empty(&debug_err_mask)) {
core_num_brps = 0;
core_num_wrps = 0;
if (ret > 0)
cpuhp_remove_state_nocalls(ret);
put_online_cpus();
cpus_read_unlock();
return 0;
}
@ -1124,7 +1125,7 @@ static int __init arch_hw_breakpoint_init(void)
TRAP_HWBKPT, "watchpoint debug exception");
hook_ifault_code(FAULT_CODE_DEBUG, hw_breakpoint_pending, SIGTRAP,
TRAP_HWBKPT, "breakpoint debug exception");
put_online_cpus();
cpus_read_unlock();
/* Register PM notifiers. */
pm_init();