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kgdb: use atomic_inc and atomic_dec instead of atomic_set 

Memory barriers should be used for the kgdb cpu synchronization.  The
atomic_set() does not imply a memory barrier.

Reported-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
This commit is contained in:
Jason Wessel 2010-04-02 14:58:18 -05:00
parent 62fae31219
commit ae6bf53e02
1 changed files with 7 additions and 8 deletions
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15
kernel/kgdb.c
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@ -1379,8 +1379,7 @@ acquirelock:
* Make sure the above info reaches the primary CPU before
* our cpu_in_kgdb[] flag setting does:
*/
smp_wmb();
atomic_set(&cpu_in_kgdb[cpu], 1);
atomic_inc(&cpu_in_kgdb[cpu]);
/*
* CPU will loop if it is a slave or request to become a kgdb
@ -1400,7 +1399,7 @@ return_normal:
*/
if (arch_kgdb_ops.correct_hw_break)
arch_kgdb_ops.correct_hw_break();
atomic_set(&cpu_in_kgdb[cpu], 0);
atomic_dec(&cpu_in_kgdb[cpu]);
touch_softlockup_watchdog_sync();
clocksource_touch_watchdog();
local_irq_restore(flags);
@ -1449,7 +1448,7 @@ return_normal:
*/
if (!kgdb_single_step) {
for (i = 0; i < NR_CPUS; i++)
atomic_set(&passive_cpu_wait[i], 1);
atomic_inc(&passive_cpu_wait[i]);
}
#ifdef CONFIG_SMP
@ -1483,11 +1482,11 @@ return_normal:
if (kgdb_io_ops->post_exception)
kgdb_io_ops->post_exception();
atomic_set(&cpu_in_kgdb[ks->cpu], 0);
atomic_dec(&cpu_in_kgdb[ks->cpu]);
if (!kgdb_single_step) {
for (i = NR_CPUS-1; i >= 0; i--)
atomic_set(&passive_cpu_wait[i], 0);
atomic_dec(&passive_cpu_wait[i]);
/*
* Wait till all the CPUs have quit
* from the debugger.
@ -1736,11 +1735,11 @@ EXPORT_SYMBOL_GPL(kgdb_unregister_io_module);
*/
void kgdb_breakpoint(void)
{
atomic_set(&kgdb_setting_breakpoint, 1);
atomic_inc(&kgdb_setting_breakpoint);
wmb(); /* Sync point before breakpoint */
arch_kgdb_breakpoint();
wmb(); /* Sync point after breakpoint */
atomic_set(&kgdb_setting_breakpoint, 0);
atomic_dec(&kgdb_setting_breakpoint);
}
EXPORT_SYMBOL_GPL(kgdb_breakpoint);