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| author | Christophe Leroy <christophe.leroy@c-s.fr> | 2019-01-31 10:08:52 +0000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2019-02-23 22:31:40 +1100 |
| commit | 018cce33c5e62dda265df8ae0ddf7f3a3357ad1f (patch) | |
| tree | 2e441439ad12b6bbf76c0e9d00bc6f0a59a24e0d /arch/powerpc/kernel/process.c | |
| parent | 054860897cd35a4e9cec953ae955b429e31e74f7 (diff) | |
| download | linux-018cce33c5e62dda265df8ae0ddf7f3a3357ad1f.tar.gz | |
powerpc: prep stack walkers for THREAD_INFO_IN_TASK
[text copied from commit 9bbd4c56b0b6
("arm64: prep stack walkers for THREAD_INFO_IN_TASK")]
When CONFIG_THREAD_INFO_IN_TASK is selected, task stacks may be freed
before a task is destroyed. To account for this, the stacks are
refcounted, and when manipulating the stack of another task, it is
necessary to get/put the stack to ensure it isn't freed and/or re-used
while we do so.
This patch reworks the powerpc stack walking code to account for this.
When CONFIG_THREAD_INFO_IN_TASK is not selected these perform no
refcounting, and this should only be a structural change that does not
affect behaviour.
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Move try_get_task_stack() below tsk == NULL check in show_stack()]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/kernel/process.c')
| -rw-r--r-- | arch/powerpc/kernel/process.c | 26 |
1 files changed, 23 insertions, 3 deletions
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index 71bad4b6f80d..791bd8ea475d 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -2027,7 +2027,7 @@ int validate_sp(unsigned long sp, struct task_struct *p, EXPORT_SYMBOL(validate_sp); -unsigned long get_wchan(struct task_struct *p) +static unsigned long __get_wchan(struct task_struct *p) { unsigned long ip, sp; int count = 0; @@ -2053,6 +2053,20 @@ unsigned long get_wchan(struct task_struct *p) return 0; } +unsigned long get_wchan(struct task_struct *p) +{ + unsigned long ret; + + if (!try_get_task_stack(p)) + return 0; + + ret = __get_wchan(p); + + put_task_stack(p); + + return ret; +} + static int kstack_depth_to_print = CONFIG_PRINT_STACK_DEPTH; void show_stack(struct task_struct *tsk, unsigned long *stack) @@ -2067,9 +2081,13 @@ void show_stack(struct task_struct *tsk, unsigned long *stack) int curr_frame = 0; #endif - sp = (unsigned long) stack; if (tsk == NULL) tsk = current; + + if (!try_get_task_stack(tsk)) + return; + + sp = (unsigned long) stack; if (sp == 0) { if (tsk == current) sp = current_stack_pointer(); @@ -2081,7 +2099,7 @@ void show_stack(struct task_struct *tsk, unsigned long *stack) printk("Call Trace:\n"); do { if (!validate_sp(sp, tsk, STACK_FRAME_OVERHEAD)) - return; + break; stack = (unsigned long *) sp; newsp = stack[0]; @@ -2121,6 +2139,8 @@ void show_stack(struct task_struct *tsk, unsigned long *stack) sp = newsp; } while (count++ < kstack_depth_to_print); + + put_task_stack(tsk); } #ifdef CONFIG_PPC64 |