50 lines
1.8 KiB
Diff
50 lines
1.8 KiB
Diff
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# Commit 7b9fa702ca323164d6b49e8b639a57f880454a8c
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# Date 2013-08-13 14:31:01 +0200
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# Author Andrew Cooper <andrew.cooper3@citrix.com>
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# Committer Jan Beulich <jbeulich@suse.com>
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watchdog/crash: Always disable watchdog in console_force_unlock()
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Depending on the state of the conring and serial_tx_buffer,
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console_force_unlock() can be a long running operation, usually because of
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serial_start_sync()
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XenServer testing has found a reliable case where console_force_unlock() on
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one PCPU takes long enough for another PCPU to timeout due to the watchdog
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(such as waiting for a tlb flush callin).
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The watchdog timeout causes the second PCPU to repeat the
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console_force_unlock(), at which point the first PCPU typically fails an
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assertion in spin_unlock_irqrestore(&port->tx_lock) (because the tx_lock has
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been unlocked behind itself).
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console_force_unlock() is only on emergency paths, so one way or another the
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host is going down. Disable the watchdog before forcing the console lock to
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help prevent having pcpus completing with each other to bring the host down.
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Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
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Acked-by: Keir Fraser <keir@xen.org>
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--- a/xen/arch/x86/x86_64/traps.c
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+++ b/xen/arch/x86/x86_64/traps.c
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@@ -226,8 +226,6 @@ void do_double_fault(struct cpu_user_reg
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unsigned int cpu;
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unsigned long crs[8];
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- watchdog_disable();
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-
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console_force_unlock();
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asm ( "lsll %1, %0" : "=r" (cpu) : "rm" (PER_CPU_GDT_ENTRY << 3) );
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--- a/xen/drivers/char/console.c
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+++ b/xen/drivers/char/console.c
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@@ -736,6 +736,9 @@ void console_end_log_everything(void)
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void console_force_unlock(void)
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{
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+#ifdef CONFIG_X86
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+ watchdog_disable();
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+#endif
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spin_lock_init(&console_lock);
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serial_force_unlock(sercon_handle);
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console_locks_busted = 1;
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