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Commit 1aabc599 authored by Steven Rostedt (Red Hat)'s avatar Steven Rostedt (Red Hat) Committed by Linus Torvalds
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x86: Fix dumpstack_64 to keep state of "used" variable in loop 



Commit 2223f6f6 "x86: Clean up dumpstack_64.c code" moved the used
variable to a local within the loop, but the in_exception_stack()
depended on being non-volatile with the ability to change it.

By always re-initializing the "used" variable to zero, it would cause
the in_exception_stack() to return the same thing each time, and
cause the dump_stack loop to go into an infinite loop.

Reported-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b33ce442

arch/x86/kernel/dumpstack_64.c

+5 −5
Original line number Diff line number Diff line
@@ -115,19 +115,18 @@ enum stack_type { 
};



static enum stack_type

analyze_stack(int cpu, struct task_struct *task,

	      unsigned long *stack, unsigned long **stack_end, char **id)

analyze_stack(int cpu, struct task_struct *task, unsigned long *stack,

	      unsigned long **stack_end, unsigned *used, char **id)

{

	unsigned long *irq_stack;

	unsigned long addr;

	unsigned used = 0;



	addr = ((unsigned long)stack & (~(THREAD_SIZE - 1)));

	if ((unsigned long)task_stack_page(task) == addr)

		return STACK_IS_NORMAL;



	*stack_end = in_exception_stack(cpu, (unsigned long)stack,

					 &used, id);

					used, id);

	if (*stack_end)

		return STACK_IS_EXCEPTION;
@@ -158,6 +157,7 @@ void dump_trace(struct task_struct *task, struct pt_regs *regs, 
	struct thread_info *tinfo;

	unsigned long *irq_stack;

	unsigned long dummy;

	unsigned used = 0;

	int graph = 0;

	int done = 0;
@@ -186,7 +186,7 @@ void dump_trace(struct task_struct *task, struct pt_regs *regs, 
		enum stack_type stype;

		char *id;



		stype = analyze_stack(cpu, task, stack, &stack_end, &id);

		stype = analyze_stack(cpu, task, stack, &stack_end, &used, &id);



		/* Default finish unless specified to continue */

		done = 1;