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Commit 81539169 authored by Josh Poimboeuf's avatar Josh Poimboeuf Committed by Ingo Molnar
Browse files

x86/dumpstack: Remove NULL task pointer convention 



show_stack_log_lvl() and friends allow a NULL pointer for the
task_struct to indicate the current task.  This creates confusion and
can cause sneaky bugs.

Instead require the caller to pass 'current' directly.

This only changes the internal workings of the dumpstack code.  The
dump_trace() and show_stack() interfaces still allow a NULL task
pointer.  Those interfaces should also probably be fixed as well.

Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent ac496bf4

arch/x86/include/asm/stacktrace.h

+2 −2
Original line number Diff line number Diff line
@@ -94,7 +94,7 @@ get_frame_pointer(struct task_struct *task, struct pt_regs *regs) 
	if (regs)

		return (unsigned long *)regs->bp;



	if (!task || task == current)

	if (task == current)

		return __builtin_frame_address(0);



	return (unsigned long *)((struct inactive_task_frame *)task->thread.sp)->bp;
@@ -113,7 +113,7 @@ get_stack_pointer(struct task_struct *task, struct pt_regs *regs) 
	if (regs)

		return (unsigned long *)kernel_stack_pointer(regs);



	if (!task || task == current)

	if (task == current)

		return __builtin_frame_address(0);



	return (unsigned long *)task->thread.sp;

arch/x86/kernel/dumpstack.c

+3 −1
Original line number Diff line number Diff line
@@ -175,11 +175,13 @@ void show_stack(struct task_struct *task, unsigned long *sp) 
{

	unsigned long bp = 0;



	task = task ? : current;



	/*

	 * Stack frames below this one aren't interesting.  Don't show them

	 * if we're printing for %current.

	 */

	if (!sp && (!task || task == current)) {

	if (!sp && task == current) {

		sp = get_stack_pointer(current, NULL);

		bp = (unsigned long)get_frame_pointer(current, NULL);

	}

arch/x86/kernel/dumpstack_32.c

+1 −1
Original line number Diff line number Diff line
@@ -205,7 +205,7 @@ void show_regs(struct pt_regs *regs) 
		u8 *ip;



		pr_emerg("Stack:\n");

		show_stack_log_lvl(NULL, regs, NULL, 0, KERN_EMERG);

		show_stack_log_lvl(current, regs, NULL, 0, KERN_EMERG);



		pr_emerg("Code:");

arch/x86/kernel/dumpstack_64.c

+1 −1
Original line number Diff line number Diff line
@@ -278,7 +278,7 @@ void show_regs(struct pt_regs *regs) 
		u8 *ip;



		printk(KERN_DEFAULT "Stack:\n");

		show_stack_log_lvl(NULL, regs, NULL, 0, KERN_DEFAULT);

		show_stack_log_lvl(current, regs, NULL, 0, KERN_DEFAULT);



		printk(KERN_DEFAULT "Code: ");