When returning from the kernel debugger allow a reset of the rcu
jiffies_stall value to prevent the rcu stall detector from sending NMI
events which stack dumps on all the cpus in the system.
Signed-off-by: Jason Wessel <jason.wes...@windriver.com>
CC: Dipankar Sarma <dipan...@in.ibm.com>
CC: Paul E. McKenney <paul...@linux.vnet.ibm.com>
CC: Ingo Molnar <mi...@elte.hu>
---
include/linux/rcupdate.h | 8 ++++++++
kernel/debug/debug_core.c | 2 ++
kernel/rcutree.c | 9 +++++++++
3 files changed, 19 insertions(+), 0 deletions(-)
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 9fbc54a..abd3ab6 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -599,4 +599,12 @@ static inline void debug_rcu_head_unqueue(struct rcu_head
*head)
#define rcu_dereference_index_check(p, c) \
__rcu_dereference_index_check((p), (c))
+#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
+extern void rcu_cpu_stall_reset(void);
+#else /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
+static inline void rcu_cpu_stall_reset(void)
+{
+}
+#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
+
#endif /* __LINUX_RCUPDATE_H */
diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index e4d6819..1600e90 100644
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -47,6 +47,7 @@
#include <linux/pid.h>
#include <linux/smp.h>
#include <linux/mm.h>
+#include <linux/rcupdate.h>
#include <asm/cacheflush.h>
#include <asm/byteorder.h>
@@ -474,6 +475,7 @@ static void dbg_touch_watchdogs(void)
{
touch_softlockup_watchdog_sync();
clocksource_touch_watchdog();
+ rcu_cpu_stall_reset();
}
static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs)
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index d5bc439..209b755 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -532,6 +532,9 @@ static void check_cpu_stall(struct rcu_state *rsp, struct
rcu_data *rdp)
if (rcu_cpu_stall_panicking)
return;
+ /* Gracefully handle a watch dog reset when jiffies_stall == 0 */
+ if (!rsp->jiffies_stall)
+ return;
delta = jiffies - rsp->jiffies_stall;
rnp = rdp->mynode;
if ((rnp->qsmask & rdp->grpmask) && delta >= 0) {
@@ -561,6 +564,12 @@ static void __init check_cpu_stall_init(void)
atomic_notifier_chain_register(&panic_notifier_list, &rcu_panic_block);
}
+void rcu_cpu_stall_reset(void)
+{
+ rcu_sched_state.jiffies_stall = 0;
+ rcu_bh_state.jiffies_stall = 0;
+}
+
#else /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
static void record_gp_stall_check_time(struct rcu_state *rsp)
--
1.6.3.3
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