Commit 42a20f86 authored by Kees Cook's avatar Kees Cook Committed by Peter Zijlstra
Browse files

sched: Add wrapper for get_wchan() to keep task blocked 



Having a stable wchan means the process must be blocked and for it to
stay that way while performing stack unwinding.

Suggested-by: default avatarPeter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarGeert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> [arm]
Tested-by: Mark Rutland <mark.rutland@arm.com> [arm64]
Link: https://lkml.kernel.org/r/20211008111626.332092234@infradead.org
parent bc9bbb81

arch/alpha/include/asm/processor.h

+1 −1
Original line number Diff line number Diff line
@@ -42,7 +42,7 @@ extern void start_thread(struct pt_regs *, unsigned long, unsigned long); 
struct task_struct;

extern void release_thread(struct task_struct *);



unsigned long get_wchan(struct task_struct *p);

unsigned long __get_wchan(struct task_struct *p);



#define KSTK_EIP(tsk) (task_pt_regs(tsk)->pc)

arch/alpha/kernel/process.c

+2 −3
Original line number Diff line number Diff line
@@ -376,12 +376,11 @@ thread_saved_pc(struct task_struct *t) 
}



unsigned long

get_wchan(struct task_struct *p)

__get_wchan(struct task_struct *p)

{

	unsigned long schedule_frame;

	unsigned long pc;

	if (!p || p == current || task_is_running(p))

		return 0;



	/*

	 * This one depends on the frame size of schedule().  Do a

	 * "disass schedule" in gdb to find the frame size.  Also, the

arch/arc/include/asm/processor.h

+1 −1
Original line number Diff line number Diff line
@@ -70,7 +70,7 @@ struct task_struct; 
extern void start_thread(struct pt_regs * regs, unsigned long pc,

			 unsigned long usp);



extern unsigned int get_wchan(struct task_struct *p);

extern unsigned int __get_wchan(struct task_struct *p);



#endif /* !__ASSEMBLY__ */

arch/arc/kernel/stacktrace.c

+2 −2
Original line number Diff line number Diff line
@@ -15,7 +15,7 @@ 
 *      = specifics of data structs where trace is saved(CONFIG_STACKTRACE etc)

 *

 *  vineetg: March 2009

 *  -Implemented correct versions of thread_saved_pc() and get_wchan()

 *  -Implemented correct versions of thread_saved_pc() and __get_wchan()

 *

 *  rajeshwarr: 2008

 *  -Initial implementation
@@ -248,7 +248,7 @@ void show_stack(struct task_struct *tsk, unsigned long *sp, const char *loglvl) 
 * Of course just returning schedule( ) would be pointless so unwind until

 * the function is not in schedular code

 */

unsigned int get_wchan(struct task_struct *tsk)

unsigned int __get_wchan(struct task_struct *tsk)

{

	return arc_unwind_core(tsk, NULL, __get_first_nonsched, NULL);

}

arch/arm/include/asm/processor.h

+1 −1
Original line number Diff line number Diff line
@@ -84,7 +84,7 @@ struct task_struct; 
/* Free all resources held by a thread. */

extern void release_thread(struct task_struct *);



unsigned long get_wchan(struct task_struct *p);

unsigned long __get_wchan(struct task_struct *p);



#define task_pt_regs(p) \

	((struct pt_regs *)(THREAD_START_SP + task_stack_page(p)) - 1)