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Subject[tip:core/stacktrace] tracing: Simplify stack trace retrieval
Commit-ID:  ee6dd0db4d8de41a0a0bc37d8d87a0b1623f83b0
Gitweb: https://git.kernel.org/tip/ee6dd0db4d8de41a0a0bc37d8d87a0b1623f83b0
Author: Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Thu, 25 Apr 2019 11:45:16 +0200
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Mon, 29 Apr 2019 12:37:55 +0200

tracing: Simplify stack trace retrieval

Replace the indirection through struct stack_trace by using the storage
array based interfaces.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: linux-mm@kvack.org
Cc: David Rientjes <rientjes@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: kasan-dev@googlegroups.com
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: iommu@lists.linux-foundation.org
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: David Sterba <dsterba@suse.com>
Cc: Chris Mason <clm@fb.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: linux-btrfs@vger.kernel.org
Cc: dm-devel@redhat.com
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: intel-gfx@lists.freedesktop.org
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: dri-devel@lists.freedesktop.org
Cc: David Airlie <airlied@linux.ie>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Tom Zanussi <tom.zanussi@linux.intel.com>
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: linux-arch@vger.kernel.org
Link: https://lkml.kernel.org/r/20190425094803.248604594@linutronix.de

---
kernel/trace/trace.c | 40 +++++++++++++---------------------------
1 file changed, 13 insertions(+), 27 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index d8369d27c1af..0ce8515dd470 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2774,22 +2774,18 @@ static void __ftrace_trace_stack(struct ring_buffer *buffer,
{
struct trace_event_call *call = &event_kernel_stack;
struct ring_buffer_event *event;
+ unsigned int size, nr_entries;
struct ftrace_stack *fstack;
struct stack_entry *entry;
- struct stack_trace trace;
- int size = FTRACE_KSTACK_ENTRIES;
int stackidx;

- trace.nr_entries = 0;
- trace.skip = skip;
-
/*
* Add one, for this function and the call to save_stack_trace()
* If regs is set, then these functions will not be in the way.
*/
#ifndef CONFIG_UNWINDER_ORC
if (!regs)
- trace.skip++;
+ skip++;
#endif

/*
@@ -2816,28 +2812,24 @@ static void __ftrace_trace_stack(struct ring_buffer *buffer,
barrier();

fstack = this_cpu_ptr(ftrace_stacks.stacks) + stackidx;
- trace.entries = fstack->calls;
- trace.max_entries = FTRACE_KSTACK_ENTRIES;
-
- if (regs)
- save_stack_trace_regs(regs, &trace);
- else
- save_stack_trace(&trace);
-
- if (trace.nr_entries > size)
- size = trace.nr_entries;
+ size = ARRAY_SIZE(fstack->calls);

- size *= sizeof(unsigned long);
+ if (regs) {
+ nr_entries = stack_trace_save_regs(regs, fstack->calls,
+ size, skip);
+ } else {
+ nr_entries = stack_trace_save(fstack->calls, size, skip);
+ }

+ size = nr_entries * sizeof(unsigned long);
event = __trace_buffer_lock_reserve(buffer, TRACE_STACK,
sizeof(*entry) + size, flags, pc);
if (!event)
goto out;
entry = ring_buffer_event_data(event);

- memcpy(&entry->caller, trace.entries, size);
-
- entry->size = trace.nr_entries;
+ memcpy(&entry->caller, fstack->calls, size);
+ entry->size = nr_entries;

if (!call_filter_check_discard(call, entry, buffer, event))
__buffer_unlock_commit(buffer, event);
@@ -2916,7 +2908,6 @@ ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags, int pc)
struct trace_event_call *call = &event_user_stack;
struct ring_buffer_event *event;
struct userstack_entry *entry;
- struct stack_trace trace;

if (!(global_trace.trace_flags & TRACE_ITER_USERSTACKTRACE))
return;
@@ -2947,12 +2938,7 @@ ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags, int pc)
entry->tgid = current->tgid;
memset(&entry->caller, 0, sizeof(entry->caller));

- trace.nr_entries = 0;
- trace.max_entries = FTRACE_STACK_ENTRIES;
- trace.skip = 0;
- trace.entries = entry->caller;
-
- save_stack_trace_user(&trace);
+ stack_trace_save_user(entry->caller, FTRACE_STACK_ENTRIES);
if (!call_filter_check_discard(call, entry, buffer, event))
__buffer_unlock_commit(buffer, event);

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