include/linux/ftrace.h | 1 - kernel/trace/fgraph.c | 54 +++++++++++++++++++++--------------------- 2 files changed, 27 insertions(+), 28 deletions(-)
This patch uses [first ... last] = value to initialize fgraph_array[].
And it declares all the callbacks in fgraph_stub as static, as they are
not called from external code.
Signed-off-by: Liao Chang <liaochang1@huawei.com>
---
include/linux/ftrace.h | 1 -
kernel/trace/fgraph.c | 54 +++++++++++++++++++++---------------------
2 files changed, 27 insertions(+), 28 deletions(-)
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index fd5e84d0ec47..76bfc5560b57 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -1039,7 +1039,6 @@ typedef void (*trace_func_graph_ret_t)(struct ftrace_graph_ret *,
typedef int (*trace_func_graph_ent_t)(struct ftrace_graph_ent *,
struct fgraph_ops *); /* entry */
-extern int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace, struct fgraph_ops *gops);
bool ftrace_pids_enabled(struct ftrace_ops *ops);
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index d7d4fb403f6f..41d14b455185 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -172,20 +172,41 @@ enum {
DEFINE_STATIC_KEY_FALSE(kill_ftrace_graph);
int ftrace_graph_active;
-static struct fgraph_ops *fgraph_array[FGRAPH_ARRAY_SIZE];
+static int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace,
+ struct fgraph_ops *gops)
+{
+ return 0;
+}
+
+static void ftrace_graph_ret_stub(struct ftrace_graph_ret *trace,
+ struct fgraph_ops *gops)
+{
+}
+
+static struct fgraph_ops fgraph_stub = {
+ .entryfunc = ftrace_graph_entry_stub,
+ .retfunc = ftrace_graph_ret_stub,
+};
+
+static struct fgraph_ops *fgraph_array[FGRAPH_ARRAY_SIZE] = {
+ [0 ... FGRAPH_ARRAY_SIZE - 1] = &fgraph_stub,
+};
static unsigned long fgraph_array_bitmask;
/* LRU index table for fgraph_array */
static int fgraph_lru_table[FGRAPH_ARRAY_SIZE];
-static int fgraph_lru_next;
-static int fgraph_lru_last;
+static int fgraph_lru_next = -1;
+static int fgraph_lru_last = -1;
/* Initialize fgraph_lru_table with unused index */
static void fgraph_lru_init(void)
{
- int i;
+ if ((fgraph_lru_next >= 0) && (fgraph_lru_last >= 0))
+ return;
- for (i = 0; i < FGRAPH_ARRAY_SIZE; i++)
+ fgraph_lru_next = fgraph_lru_last = 0;
+
+ for (int i = 0; i < FGRAPH_ARRAY_SIZE; i++)
fgraph_lru_table[i] = i;
}
@@ -483,22 +504,6 @@ int __weak ftrace_disable_ftrace_graph_caller(void)
}
#endif
-int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace,
- struct fgraph_ops *gops)
-{
- return 0;
-}
-
-static void ftrace_graph_ret_stub(struct ftrace_graph_ret *trace,
- struct fgraph_ops *gops)
-{
-}
-
-static struct fgraph_ops fgraph_stub = {
- .entryfunc = ftrace_graph_entry_stub,
- .retfunc = ftrace_graph_ret_stub,
-};
-
static struct fgraph_ops *fgraph_direct_gops = &fgraph_stub;
DEFINE_STATIC_CALL(fgraph_func, ftrace_graph_entry_stub);
DEFINE_STATIC_CALL(fgraph_retfunc, ftrace_graph_ret_stub);
@@ -1250,12 +1255,7 @@ int register_ftrace_graph(struct fgraph_ops *gops)
mutex_lock(&ftrace_lock);
- if (!fgraph_array[0]) {
- /* The array must always have real data on it */
- for (i = 0; i < FGRAPH_ARRAY_SIZE; i++)
- fgraph_array[i] = &fgraph_stub;
- fgraph_lru_init();
- }
+ fgraph_lru_init();
i = fgraph_lru_alloc_index();
if (i < 0 || WARN_ON_ONCE(fgraph_array[i] != &fgraph_stub)) {
--
2.34.1On Thu, 12 Sep 2024 11:15:50 +0000 Liao Chang <liaochang1@huawei.com> wrote: > This patch uses [first ... last] = value to initialize fgraph_array[]. > And it declares all the callbacks in fgraph_stub as static, as they are > not called from external code. This patch doesn't look like a simplification, and it is incorrect about the "not called from external code" as the kernel test robot pointed out! -- Steve
在 2024/9/28 8:17, Steven Rostedt 写道: > On Thu, 12 Sep 2024 11:15:50 +0000 > Liao Chang <liaochang1@huawei.com> wrote: > >> This patch uses [first ... last] = value to initialize fgraph_array[]. >> And it declares all the callbacks in fgraph_stub as static, as they are >> not called from external code. > > This patch doesn't look like a simplification, and it is incorrect > about the "not called from external code" as the kernel test robot > pointed out! Yes, I overlooked the external call, the static keyword is removed in the next revision. The patch just makes code neat, it isn't a real simplification. > > -- Steve > -- BR Liao, Chang
Hi Liao, kernel test robot noticed the following build errors: [auto build test ERROR on linus/master] [also build test ERROR on v6.11-rc7 next-20240913] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch#_base_tree_information] url: https://github.com/intel-lab-lkp/linux/commits/Liao-Chang/function_graph-Simplify-the-initialization-of-fgraph-LRU-data/20240912-193159 base: linus/master patch link: https://lore.kernel.org/r/20240912111550.1752115-1-liaochang1%40huawei.com patch subject: [PATCH] function_graph: Simplify the initialization of fgraph LRU data config: arm-randconfig-004-20240913 (https://download.01.org/0day-ci/archive/20240914/202409140325.G1zsZ0jL-lkp@intel.com/config) compiler: clang version 20.0.0git (https://github.com/llvm/llvm-project bf684034844c660b778f0eba103582f582b710c9) reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240914/202409140325.G1zsZ0jL-lkp@intel.com/reproduce) If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags | Reported-by: kernel test robot <lkp@intel.com> | Closes: https://lore.kernel.org/oe-kbuild-all/202409140325.G1zsZ0jL-lkp@intel.com/ All errors (new ones prefixed by >>): >> ld.lld: error: undefined symbol: ftrace_graph_entry_stub >>> referenced by arch/arm/kernel/entry-ftrace.o:(.text+0xB8) in archive vmlinux.a -- 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests/wiki
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