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authorJason Wessel <jason.wessel@windriver.com>2010-05-21 08:46:00 -0500
committerJason Wessel <jason.wessel@windriver.com>2010-10-22 15:34:13 -0500
commit495363d380b4f4745bd8677912688654afc44020 (patch)
tree647032c22f9e77f91578dcae864776849dbcbfa8 /kernel/debug/debug_core.c
parentdfee3a7b92208b30f77876068aece9ea571270c2 (diff)
downloadlinux-495363d380b4f4745bd8677912688654afc44020.tar.bz2
kdb,debug_core: adjust master cpu switch logic against new debug_core locking
The kdb shell needs to enforce switching back to the original CPU that took the exception before restoring normal kernel execution. Resuming from a different CPU than what took the original exception will cause problems with spin locks that are freed from the a different processor than had taken the lock. The special logic in dbg_cpu_switch() can go away entirely with because the state of what cpus want to be masters or slaves will remain unchanged between entry and exit of the debug_core exception context. Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Diffstat (limited to 'kernel/debug/debug_core.c')
-rw-r--r--kernel/debug/debug_core.c16
1 files changed, 2 insertions, 14 deletions
diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index 26dbdc37d219..fec596da9bd0 100644
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -460,19 +460,6 @@ static int kgdb_reenter_check(struct kgdb_state *ks)
return 1;
}
-static void dbg_cpu_switch(int cpu, int next_cpu)
-{
- /* Mark the cpu we are switching away from as a slave when it
- * holds the kgdb_active token. This must be done so that the
- * that all the cpus wait in for the debug core will not enter
- * again as the master. */
- if (cpu == atomic_read(&kgdb_active)) {
- kgdb_info[cpu].exception_state |= DCPU_IS_SLAVE;
- kgdb_info[cpu].exception_state &= ~DCPU_WANT_MASTER;
- }
- kgdb_info[next_cpu].exception_state |= DCPU_NEXT_MASTER;
-}
-
static void dbg_touch_watchdogs(void)
{
touch_softlockup_watchdog_sync();
@@ -638,7 +625,8 @@ cpu_master_loop:
if (error == DBG_PASS_EVENT) {
dbg_kdb_mode = !dbg_kdb_mode;
} else if (error == DBG_SWITCH_CPU_EVENT) {
- dbg_cpu_switch(cpu, dbg_switch_cpu);
+ kgdb_info[dbg_switch_cpu].exception_state |=
+ DCPU_NEXT_MASTER;
goto cpu_loop;
} else {
kgdb_info[cpu].ret_state = error;