Attachment 310406 Details for Bug 430452 – sysrq-w deadlock fix patch

[patch] sysrq-w deadlock fix patch

linux-2.6.9-sysrq-w-deadlock-fix.patch (text/plain), 4.90 KB, created by Makito SHIOKAWA on 2008-06-27 01:59:35 UTC

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Creator: Makito SHIOKAWA

Created: 2008-06-27 01:59:35 UTC

Size: 4.90 KB

patch

obsolete

>--- linux-2.6.9/include/linux/smp.h.orig	2008-01-31 20:04:55.000000000 +0900
>+++ linux-2.6.9/include/linux/smp.h	2008-01-31 20:56:34.000000000 +0900
>@@ -53,6 +53,10 @@ extern void smp_cpus_done(unsigned int m
>  */
> extern int smp_call_function (void (*func) (void *info), void *info,
> 			      int retry, int wait);
>+#if defined(__i386__) || defined(__x86_64__)
>+extern int smp_call_function_trylock (void (*func) (void *info), void *info,
>+			      int retry, int wait);
>+#endif
> extern void dump_smp_call_function (void (*func) (void *info), void *info);
> 
> /*
>@@ -101,6 +105,9 @@ void smp_prepare_boot_cpu(void);
>  
> #define smp_threads_ready			1
> #define smp_call_function(func,info,retry,wait)	({ 0; })
>+#if defined(__i386__) || defined(__x86_64__)
>+#define smp_call_function_trylock(func,info,retry,wait)	({ 0; })
>+#endif
> static inline void dump_smp_call_function(void (*func) (void *info), void *info) { }
> #define on_each_cpu(func,info,retry,wait)	({ func(info); 0; })
> static inline void smp_send_reschedule(int cpu) { }
>--- linux-2.6.9/arch/i386/kernel/smp.c.orig	2008-01-31 20:05:02.000000000 +0900
>+++ linux-2.6.9/arch/i386/kernel/smp.c	2008-01-31 20:56:58.000000000 +0900
>@@ -634,6 +634,64 @@ int smp_call_function (void (*func) (voi
> 	return 0;
> }
> 
>+/*
>+ * This function is copy of smp_call_function() which uses spin_trylock() 
>+ * instead of spin_lock().
>+ * Returns -EBUSY on failure of getting call_lock.
>+ */
>+
>+int smp_call_function_trylock (void (*func) (void *info), void *info, int nonatomic,
>+			int wait)
>+/*
>+ * [SUMMARY] Run a function on all other CPUs.
>+ * <func> The function to run. This must be fast and non-blocking.
>+ * <info> An arbitrary pointer to pass to the function.
>+ * <nonatomic> currently unused.
>+ * <wait> If true, wait (atomically) until function has complete on other CPUs.
>+ * [RETURNS] 0 on success, else a negative status code on failure of getting 
>+ * call_lock.
>+ *
>+ * You must not call this function with disabled interrupts or from a
>+ * hardware interrupt handler or from a bottom half handler.
>+ */
>+{
>+	struct call_data_struct data;
>+	int cpus = num_online_cpus()-1;
>+
>+	if (!cpus)
>+		return 0;
>+
>+	/* Can deadlock when called with interrupts disabled */
>+	/* Only if we are waiting for other CPU to ack */
>+	WARN_ON(irqs_disabled() && wait >= 0);
>+
>+	data.func = func;
>+	data.info = info;
>+	atomic_set(&data.started, 0);
>+	data.wait = wait;
>+	if (wait)
>+		atomic_set(&data.finished, 0);
>+
>+	if (!spin_trylock(&call_lock))
>+		return -EBUSY;
>+	call_data = &data;
>+	mb();
>+	
>+	/* Send a message to all other CPUs and wait for them to respond */
>+	send_IPI_allbutself(CALL_FUNCTION_VECTOR);
>+
>+	/* Wait for response */
>+	while (atomic_read(&data.started) != cpus)
>+		cpu_relax();
>+
>+	if (wait)
>+		while (atomic_read(&data.finished) != cpus)
>+			cpu_relax();
>+	spin_unlock(&call_lock);
>+
>+	return 0;
>+}
>+
> static void stop_this_cpu (void * dummy)
> {
> 	/*
>--- linux-2.6.9/arch/x86_64/kernel/smp.c.orig	2008-01-31 20:05:47.000000000 +0900
>+++ linux-2.6.9/arch/x86_64/kernel/smp.c	2008-01-31 20:57:20.000000000 +0900
>@@ -399,6 +399,36 @@ int smp_call_function (void (*func) (voi
> 	return 0;
> }
> 
>+/*
>+ * This function is copy of smp_call_function() which uses spin_trylock() 
>+ * instead of spin_lock().
>+ * Returns -EBUSY on failure of getting call_lock.
>+ */
>+
>+/*
>+ * smp_call_function_trylock - run a function on all other CPUs.
>+ * @func: The function to run. This must be fast and non-blocking.
>+ * @info: An arbitrary pointer to pass to the function.
>+ * @nonatomic: currently unused.
>+ * <wait> If true, wait (atomically) until function has complete on other CPUs.
>+ *
>+ * Returns 0 on success, else a negative status code on failure of getting 
>+ * call_lock.
>+ *
>+ * You must not call this function with disabled interrupts or from a
>+ * hardware interrupt handler or from a bottom half handler.
>+ * Actually there are a few legal cases, like panic.
>+ */
>+int smp_call_function_trylock (void (*func) (void *info), void *info, int nonatomic,
>+			int wait)
>+{
>+	if (!spin_trylock(&call_lock))
>+		return -EBUSY;
>+	__smp_call_function(func,info,nonatomic,wait);
>+	spin_unlock(&call_lock);
>+	return 0;
>+}
>+
> void smp_stop_cpu(void)
> {
> 	/*
>--- linux-2.6.9/drivers/char/sysrq.c.orig	2008-01-31 20:05:52.000000000 +0900
>+++ linux-2.6.9/drivers/char/sysrq.c	2008-01-31 20:57:28.000000000 +0900
>@@ -196,7 +196,15 @@ static void showacpu(void *info)
> static void sysrq_handle_showcpus(int key, struct pt_regs *pt_regs,
> 				  struct tty_struct *tty) {
> 	showacpu(NULL);
>+#if defined(__i386__) || defined(__x86_64__)
>+	/* Call copy of smp_call_function() which uses spin_trylock()
>+	   instead of spin_lock() to avoid deadlock between other 
>+	   smp_call_function() call */
>+	if (smp_call_function_trylock(showacpu, NULL, 0, 0) == -EBUSY)
>+		printk("SysRq : Show CPUs aborted to avoid deadlock, please try again.\n");
>+#else
> 	smp_call_function(showacpu, NULL, 0, 0);
>+#endif
> }
> static struct sysrq_key_op sysrq_showcpus_op = {
> 	handler:	sysrq_handle_showcpus,

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Attachments on bug 430452: 307045 | 310406