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x86: Fix dumpstack_64 to keep state of "used" variable in loop 

Commit 2223f6f6ee "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: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
hifive-unleashed-5.1
Steven Rostedt (Red Hat) 2014-04-02 13:26:40 -04:00 committed by Linus Torvalds
parent b33ce44299
commit 1aabc5990d
1 changed files with 5 additions and 5 deletions
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10
arch/x86/kernel/dumpstack_64.c
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@ -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;