We schedule to system_wq, which has max_active=256, from
Documentation/workqueue.txt:
@max_active determines the maximum number of execution contexts per
CPU which can be assigned to the work items of a wq. For example,
with @max_active of 16, at most 16 work items of the wq can be
executing at the same time per CPU.
So for each workqueue we have a pool of processes handling scheduled
works on it, and sleeping in one process waiting for fsync will still
allow other works to run.
==
Second thing - I will try use kernel_write instead of just
file->f_op->write and resend.
On 07/19/2017 12:03 PM, Pavel Tikhomirov wrote:
As we do reboot and halt actions in scope of scheduled worker
it can never happen if scheduling does not work properly, so
panic in case that previous action was not successful.
https://jira.sw.ru/browse/PSBM-54747
Signed-off-by: Pavel Tikhomirov <[email protected]>
---
kernel/fence-watchdog.c | 20 +++++++++++++++++---
1 file changed, 17 insertions(+), 3 deletions(-)
diff --git a/kernel/fence-watchdog.c b/kernel/fence-watchdog.c
index 607045a..3ee5b89 100644
--- a/kernel/fence-watchdog.c
+++ b/kernel/fence-watchdog.c
@@ -42,7 +42,14 @@ const char *action_names[] = {"crash", "reboot", "halt",
"netfilter", NULL};
DEFINE_VVAR(volatile unsigned long, fence_wdog_jiffies64) = MAX_U64;
static int fence_wdog_action = FENCE_WDOG_CRASH;
-static atomic_t not_fenced = ATOMIC_INIT(-1);
+
+enum {
+ NOT_FENCED = 0,
+ FENCED = 1,
+ FENCED_TIMEOUT = 2,
+};
+
+static atomic_t fence_stage = ATOMIC_INIT(NOT_FENCED);
static char fence_wdog_log_path[PATH_MAX] = "/fence_wdog.log";
#define MSG_LEN 32
@@ -114,19 +121,26 @@ static DECLARE_WORK(halt_or_reboot_work,
do_halt_or_reboot);
void fence_wdog_do_fence(void)
{
- if (fence_wdog_action == FENCE_WDOG_CRASH)
+ if (fence_wdog_action == FENCE_WDOG_CRASH ||
+ atomic_read(&fence_stage) == FENCED_TIMEOUT)
panic("fence-watchdog: %s\n",
action_names[fence_wdog_action]);
else
schedule_work(&halt_or_reboot_work);
}
+#define FENCE_WDOG_TIMEOUT 30
+
inline int fence_wdog_check_timer(void)
{
if (unlikely(get_jiffies_64() > fence_wdog_jiffies64 &&
fence_wdog_action != FENCE_WDOG_NETFILTER)) {
- if (atomic_inc_not_zero(¬_fenced))
+ if (atomic_cmpxchg(&fence_stage, NOT_FENCED, FENCED) ==
NOT_FENCED
+ || (get_jiffies_64() > fence_wdog_jiffies64
+ + FENCE_WDOG_TIMEOUT * HZ
+ && atomic_cmpxchg(&fence_stage, FENCED, FENCED_TIMEOUT) ==
FENCED))
fence_wdog_do_fence();
+
return 1;
}
--
Best regards, Tikhomirov Pavel
Software Developer, Virtuozzo.
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