Commit 5572ad8f authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'trace-v6.19-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace 

Pull tracing fixes from Steven Rostedt:

 - Remove useless assignment of soft_mode variable

   The function __ftrace_event_enable_disable() sets "soft_mode" in one
   of the branch paths but doesn't use it after that. Remove the setting
   of that variable.

 - Add a cond_resched() in ring_buffer_resize()

   The resize function that allocates all the pages for the ring buffer
   was causing a soft lockup on PREEMPT_NONE configs when allocating
   large buffers on machines with many CPUs. Hopefully this is the last
   cond_resched() needed to be added as PREEMPT_LAZY becomes the norm in
   the future.

 - Make ftrace_graph_ent depth field signed

   The "depth" field of struct ftrace_graph_ent was converted from "int"
   to "unsigned long" for alignment reasons to work with being embedded
   in other structures. The conversion from a signed to unsigned caused
   integrity checks to always pass as they were comparing "depth" to
   less than zero. Make the field signed long.

 - Add recursion protection to stack trace events

   A infinite recursion was triggered by a stack trace event calling RCU
   which internally called rcu_read_unlock_special(), which triggered an
   event that was also doing stacktraces which cause it to trigger the
   same RCU lock that called rcu_read_unlock_special() again.

   Update the trace_test_and_set_recursion() to add a set of context
   checks for events to use, and have the stack trace event use that for
   recursion protection.

 - Make the variable ftrace_dump_on_oops static

   The cleanup of sysctl that moved all the updates to the files that
   use them moved the reference of ftrace_dump_on_oops to where it is
   used. It is no longer used outside of the trace.c file. Make it
   static.

* tag 'trace-v6.19-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  trace: ftrace_dump_on_oops[] is not exported, make it static
  tracing: Add recursion protection in kernel stack trace recording
  ftrace: Make ftrace_graph_ent depth field signed
  ring-buffer: Avoid softlockup in ring_buffer_resize() during memory free
  tracing: Drop unneeded assignment to soft_mode
parents f2a3b12b 1e2ed4bf

include/linux/ftrace.h

+1 −1
Original line number Diff line number Diff line
@@ -1167,7 +1167,7 @@ static inline void ftrace_init(void) { } 
 */

struct ftrace_graph_ent {

	unsigned long func; /* Current function */

	unsigned long depth;

	long depth; /* signed to check for less than zero */

} __packed;



/*

include/linux/trace_recursion.h

+9 −0
Original line number Diff line number Diff line
@@ -34,6 +34,13 @@ enum { 
	TRACE_INTERNAL_SIRQ_BIT,

	TRACE_INTERNAL_TRANSITION_BIT,



	/* Internal event use recursion bits */

	TRACE_INTERNAL_EVENT_BIT,

	TRACE_INTERNAL_EVENT_NMI_BIT,

	TRACE_INTERNAL_EVENT_IRQ_BIT,

	TRACE_INTERNAL_EVENT_SIRQ_BIT,

	TRACE_INTERNAL_EVENT_TRANSITION_BIT,



	TRACE_BRANCH_BIT,

/*

 * Abuse of the trace_recursion.
@@ -58,6 +65,8 @@ enum { 


#define TRACE_LIST_START	TRACE_INTERNAL_BIT



#define TRACE_EVENT_START	TRACE_INTERNAL_EVENT_BIT



#define TRACE_CONTEXT_MASK	((1 << (TRACE_LIST_START + TRACE_CONTEXT_BITS)) - 1)



/*

kernel/trace/ring_buffer.c

+2 −0
Original line number Diff line number Diff line
@@ -3137,6 +3137,8 @@ int ring_buffer_resize(struct trace_buffer *buffer, unsigned long size, 
					list) {

			list_del_init(&bpage->list);

			free_buffer_page(bpage);



			cond_resched();

		}

	}

 out_err_unlock:

kernel/trace/trace.c

+7 −1
Original line number Diff line number Diff line
@@ -138,7 +138,7 @@ cpumask_var_t __read_mostly tracing_buffer_mask; 
 * by commas.

 */

/* Set to string format zero to disable by default */

char ftrace_dump_on_oops[MAX_TRACER_SIZE] = "0";

static char ftrace_dump_on_oops[MAX_TRACER_SIZE] = "0";



/* When set, tracing will stop when a WARN*() is hit */

static int __disable_trace_on_warning;
@@ -3012,6 +3012,11 @@ static void __ftrace_trace_stack(struct trace_array *tr, 
	struct ftrace_stack *fstack;

	struct stack_entry *entry;

	int stackidx;

	int bit;



	bit = trace_test_and_set_recursion(_THIS_IP_, _RET_IP_, TRACE_EVENT_START);

	if (bit < 0)

		return;



	/*

	 * Add one, for this function and the call to save_stack_trace()
@@ -3080,6 +3085,7 @@ static void __ftrace_trace_stack(struct trace_array *tr, 
	/* Again, don't let gcc optimize things here */

	barrier();

	__this_cpu_dec(ftrace_stack_reserve);

	trace_clear_recursion(bit);

}



static inline void ftrace_trace_stack(struct trace_array *tr,

kernel/trace/trace_events.c

+3 −4
Original line number Diff line number Diff line
@@ -826,16 +826,15 @@ static int __ftrace_event_enable_disable(struct trace_event_file *file, 
		 * When soft_disable is set and enable is set, we want to

		 * register the tracepoint for the event, but leave the event

		 * as is. That means, if the event was already enabled, we do

		 * nothing (but set soft_mode). If the event is disabled, we

		 * set SOFT_DISABLED before enabling the event tracepoint, so

		 * it still seems to be disabled.

		 * nothing. If the event is disabled, we set SOFT_DISABLED

		 * before enabling the event tracepoint, so it still seems

		 * to be disabled.

		 */

		if (!soft_disable)

			clear_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &file->flags);

		else {

			if (atomic_inc_return(&file->sm_ref) > 1)

				break;

			soft_mode = true;

			/* Enable use of trace_buffered_event */

			trace_buffered_event_enable();

		}