From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>
Subject: [for-next][PATCH 02/17] ftrace: Add ftrace_test_recursion_trylock() helper function
Date: Wed, 11 Nov 2020 19:32:46 -0500 [thread overview]
Message-ID: <20201112003333.479947351@goodmis.org> (raw)
In-Reply-To: 20201112003244.764326960@goodmis.org
From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
To make it easier for ftrace callbacks to have recursion protection, provide
a ftrace_test_recursion_trylock() and ftrace_test_recursion_unlock() helper
that tests for recursion.
Link: https://lkml.kernel.org/r/20201028115612.634927593@goodmis.org
Link: https://lkml.kernel.org/r/20201106023546.378584067@goodmis.org
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
include/linux/trace_recursion.h | 25 +++++++++++++++++++++++++
kernel/trace/trace_functions.c | 12 +++++-------
2 files changed, 30 insertions(+), 7 deletions(-)
diff --git a/include/linux/trace_recursion.h b/include/linux/trace_recursion.h
index dbb7b6d4c94c..f2a949dbfec7 100644
--- a/include/linux/trace_recursion.h
+++ b/include/linux/trace_recursion.h
@@ -183,5 +183,30 @@ static __always_inline void trace_clear_recursion(int bit)
current->trace_recursion = val;
}
+/**
+ * ftrace_test_recursion_trylock - tests for recursion in same context
+ *
+ * Use this for ftrace callbacks. This will detect if the function
+ * tracing recursed in the same context (normal vs interrupt),
+ *
+ * Returns: -1 if a recursion happened.
+ * >= 0 if no recursion
+ */
+static __always_inline int ftrace_test_recursion_trylock(void)
+{
+ return trace_test_and_set_recursion(TRACE_FTRACE_START, TRACE_FTRACE_MAX);
+}
+
+/**
+ * ftrace_test_recursion_unlock - called when function callback is complete
+ * @bit: The return of a successful ftrace_test_recursion_trylock()
+ *
+ * This is used at the end of a ftrace callback.
+ */
+static __always_inline void ftrace_test_recursion_unlock(int bit)
+{
+ trace_clear_recursion(bit);
+}
+
#endif /* CONFIG_TRACING */
#endif /* _LINUX_TRACE_RECURSION_H */
diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
index 2c2126e1871d..943756c01190 100644
--- a/kernel/trace/trace_functions.c
+++ b/kernel/trace/trace_functions.c
@@ -141,22 +141,20 @@ function_trace_call(unsigned long ip, unsigned long parent_ip,
if (unlikely(!tr->function_enabled))
return;
+ bit = ftrace_test_recursion_trylock();
+ if (bit < 0)
+ return;
+
pc = preempt_count();
preempt_disable_notrace();
- bit = trace_test_and_set_recursion(TRACE_FTRACE_START, TRACE_FTRACE_MAX);
- if (bit < 0)
- goto out;
-
cpu = smp_processor_id();
data = per_cpu_ptr(tr->array_buffer.data, cpu);
if (!atomic_read(&data->disabled)) {
local_save_flags(flags);
trace_function(tr, ip, parent_ip, flags, pc);
}
- trace_clear_recursion(bit);
-
- out:
+ ftrace_test_recursion_unlock(bit);
preempt_enable_notrace();
}
--
2.28.0
next prev parent reply other threads:[~2020-11-12 1:43 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-12 0:32 [for-next][PATCH 00/17] tracing: Updates for 5.11 Steven Rostedt
2020-11-12 0:32 ` [for-next][PATCH 01/17] ftrace: Move the recursion testing into global headers Steven Rostedt
2020-11-12 0:32 ` Steven Rostedt [this message]
2020-11-12 0:32 ` [for-next][PATCH 03/17] ftrace: Optimize testing what context current is in Steven Rostedt
2020-11-12 0:32 ` [for-next][PATCH 04/17] pstore/ftrace: Add recursion protection to the ftrace callback Steven Rostedt
2020-11-12 0:32 ` [for-next][PATCH 05/17] kprobes/ftrace: " Steven Rostedt
2020-11-12 0:32 ` [for-next][PATCH 06/17] livepatch/ftrace: " Steven Rostedt
2020-11-12 0:32 ` [for-next][PATCH 07/17] livepatch: Trigger WARNING if livepatch function fails due to recursion Steven Rostedt
2020-11-12 0:32 ` [for-next][PATCH 08/17] perf/ftrace: Add recursion protection to the ftrace callback Steven Rostedt
2020-11-12 0:32 ` [for-next][PATCH 09/17] perf/ftrace: Check for rcu_is_watching() in callback function Steven Rostedt
2020-11-12 0:32 ` [for-next][PATCH 10/17] ftrace: Reverse what the RECURSION flag means in the ftrace_ops Steven Rostedt
2020-11-12 0:32 ` [for-next][PATCH 11/17] ftrace: Add recording of functions that caused recursion Steven Rostedt
2020-11-12 0:32 ` [for-next][PATCH 12/17] fgraph: Make overruns 4 bytes in graph stack structure Steven Rostedt
2020-11-12 9:18 ` David Laight
2020-11-12 14:39 ` Steven Rostedt
2020-11-12 0:32 ` [for-next][PATCH 13/17] ftrace: Clean up the recursion code a bit Steven Rostedt
2020-11-12 0:32 ` [for-next][PATCH 14/17] ring-buffer: Add recording of ring buffer recursion into recursed_functions Steven Rostedt
2020-11-12 0:32 ` [for-next][PATCH 15/17] ftrace: Remove unused varible ret Steven Rostedt
2020-11-12 0:33 ` [for-next][PATCH 16/17] tracing: Fix some typos in comments Steven Rostedt
2020-11-12 0:33 ` [for-next][PATCH 17/17] MAINTAINERS: assign ./fs/tracefs to TRACING Steven Rostedt
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