The patch titled
Subject: printk/nmi: use IRQ work only when ready
has been added to the -mm tree. Its filename is
printk-nmi-use-irq-work-only-when-ready.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/printk-nmi-use-irq-work-only-when-ready.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/printk-nmi-use-irq-work-only-when-ready.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Petr Mladek <pmladek@xxxxxxxx>
Subject: printk/nmi: use IRQ work only when ready
NMIs could happen at any time. This patch makes sure that the safe
printk() in NMI will schedule IRQ work only when the related structs are
initialized.
All pending messages are flushed when the IRQ work is being initialized.
Signed-off-by: Petr Mladek <pmladek@xxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
Cc: Daniel Thompson <daniel.thompson@xxxxxxxxxx>
Cc: Jiri Kosina <jkosina@xxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Cc: David Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/printk/nmi.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
diff -puN kernel/printk/nmi.c~printk-nmi-use-irq-work-only-when-ready kernel/printk/nmi.c
--- a/kernel/printk/nmi.c~printk-nmi-use-irq-work-only-when-ready
+++ a/kernel/printk/nmi.c
@@ -38,6 +38,7 @@
* were handled or when IRQs are blocked.
*/
DEFINE_PER_CPU(printk_func_t, printk_func) = vprintk_default;
+static int printk_nmi_irq_ready;
#define NMI_LOG_BUF_LEN (4096 - sizeof(atomic_t) - sizeof(struct irq_work))
@@ -83,8 +84,11 @@ again:
goto again;
/* Get flushed in a more safe context. */
- if (add)
+ if (add && printk_nmi_irq_ready) {
+ /* Make sure that IRQ work is really initialized. */
+ smp_rmb();
irq_work_queue(&s->work);
+ }
return add;
}
@@ -190,6 +194,13 @@ void __init printk_nmi_init(void)
init_irq_work(&s->work, __printk_nmi_flush);
}
+
+ /* Make sure that IRQ works are initialized before enabling. */
+ smp_wmb();
+ printk_nmi_irq_ready = 1;
+
+ /* Flush pending messages that did not have scheduled IRQ works. */
+ printk_nmi_flush();
}
void printk_nmi_enter(void)
_
Patches currently in -mm which might be from pmladek@xxxxxxxx are
printk-nmi-generic-solution-for-safe-printk-in-nmi.patch
printk-nmi-use-irq-work-only-when-ready.patch
printk-nmi-warn-when-some-message-has-been-lost-in-nmi-context.patch
printk-nmi-increase-the-size-of-nmi-buffer-and-make-it-configurable.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
