[PATCH 1/3] tracing: Fix double free when function profile init failed

[PATCH 1/3] tracing: Fix double free when function profile init failed

[Namhyung Kim]

From: Namhyung Kim <namhyung.kim@lge.com>

On the failure path, stat->start and stat->pages will refer same page.
So it'll attempt to free the same page again and get kernel panic.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 kernel/trace/ftrace.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 25770824598f..65bc47472b1b 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -694,7 +694,6 @@ int ftrace_profile_pages_init(struct ftrace_profile_stat *stat)
 		free_page(tmp);
 	}
 
-	free_page((unsigned long)stat->pages);
 	stat->pages = NULL;
 	stat->start = NULL;
 
-- 
1.7.11.7

[PATCH 2/3] tracing: Fix off-by-one on allocating stat->pages

[Namhyung Kim]

From: Namhyung Kim <namhyung.kim@lge.com>

The first page was allocated separately, so no need to start from 0.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 kernel/trace/ftrace.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 65bc47472b1b..d38ad7145f2f 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -676,7 +676,7 @@ int ftrace_profile_pages_init(struct ftrace_profile_stat *stat)
 
 	pages = DIV_ROUND_UP(functions, PROFILES_PER_PAGE);
 
-	for (i = 0; i < pages; i++) {
+	for (i = 1; i < pages; i++) {
 		pg->next = (void *)get_zeroed_page(GFP_KERNEL);
 		if (!pg->next)
 			goto out_free;
-- 
1.7.11.7

[PATCH 3/3] ftrace: Constify ftrace_profile_bits

[Namhyung Kim]

From: Namhyung Kim <namhyung.kim@lge.com>

It seems that function profiler's hash size is fixed at 1024.
Make the ftrace_profile_bits const and update hash size macro.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 kernel/trace/ftrace.c | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index d38ad7145f2f..08bbc5952a3a 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -486,7 +486,6 @@ struct ftrace_profile_stat {
 #define PROFILES_PER_PAGE					\
 	(PROFILE_RECORDS_SIZE / sizeof(struct ftrace_profile))
 
-static int ftrace_profile_bits __read_mostly;
 static int ftrace_profile_enabled __read_mostly;
 
 /* ftrace_profile_lock - synchronize the enable and disable of the profiler */
@@ -494,7 +493,10 @@ static DEFINE_MUTEX(ftrace_profile_lock);
 
 static DEFINE_PER_CPU(struct ftrace_profile_stat, ftrace_profile_stats);
 
-#define FTRACE_PROFILE_HASH_SIZE 1024 /* must be power of 2 */
+#define FTRACE_PROFILE_HASH_BITS 10
+#define FTRACE_PROFILE_HASH_SIZE (1 << FTRACE_PROFILE_HASH_BITS)
+
+static const int ftrace_profile_bits = FTRACE_PROFILE_HASH_BITS;
 
 static void *
 function_stat_next(void *v, int idx)
@@ -724,13 +726,6 @@ static int ftrace_profile_init_cpu(int cpu)
 	if (!stat->hash)
 		return -ENOMEM;
 
-	if (!ftrace_profile_bits) {
-		size--;
-
-		for (; size; size >>= 1)
-			ftrace_profile_bits++;
-	}
-
 	/* Preallocate the function profiling pages */
 	if (ftrace_profile_pages_init(stat) < 0) {
 		kfree(stat->hash);
-- 
1.7.11.7

Re: [PATCH 3/3] ftrace: Constify ftrace_profile_bits

[Steven Rostedt]

On Mon, 2013-04-01 at 21:46 +0900, Namhyung Kim wrote:
> From: Namhyung Kim <namhyung.kim@lge.com>
> 
> It seems that function profiler's hash size is fixed at 1024.
> Make the ftrace_profile_bits const and update hash size macro.
> 

Thanks for the fixes. As patch 1/3 fixes a real bug (one that can cause
a panic), I've labeled it as stable and will push it for 3.9.

Patch 2/3 just saves memory. I'll mark it stable, but it can wait to go
into 3.10.

This patch is more of a clean up, and will only go into 3.10.

Thanks!

-- Steve

Re: [PATCH 3/3] ftrace: Constify ftrace_profile_bits

[Steven Rostedt]

On Mon, 2013-04-01 at 21:46 +0900, Namhyung Kim wrote:
> From: Namhyung Kim <namhyung.kim@lge.com>
> 
> It seems that function profiler's hash size is fixed at 1024.
> Make the ftrace_profile_bits const and update hash size macro.
> 
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> ---
>  kernel/trace/ftrace.c | 13 ++++---------
>  1 file changed, 4 insertions(+), 9 deletions(-)
> 
> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> index d38ad7145f2f..08bbc5952a3a 100644
> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -486,7 +486,6 @@ struct ftrace_profile_stat {
>  #define PROFILES_PER_PAGE					\
>  	(PROFILE_RECORDS_SIZE / sizeof(struct ftrace_profile))
>  
> -static int ftrace_profile_bits __read_mostly;
>  static int ftrace_profile_enabled __read_mostly;
>  
>  /* ftrace_profile_lock - synchronize the enable and disable of the profiler */
> @@ -494,7 +493,10 @@ static DEFINE_MUTEX(ftrace_profile_lock);
>  
>  static DEFINE_PER_CPU(struct ftrace_profile_stat, ftrace_profile_stats);
>  
> -#define FTRACE_PROFILE_HASH_SIZE 1024 /* must be power of 2 */
> +#define FTRACE_PROFILE_HASH_BITS 10
> +#define FTRACE_PROFILE_HASH_SIZE (1 << FTRACE_PROFILE_HASH_BITS)
> +
> +static const int ftrace_profile_bits = FTRACE_PROFILE_HASH_BITS;

Actually, can you resubmit this, and remove ftrace_profile_bits totally,
and just use FTRACE_PROFILE_HASH_BITS directly?

Thanks,

-- Steve

>  
>  static void *
>  function_stat_next(void *v, int idx)
> @@ -724,13 +726,6 @@ static int ftrace_profile_init_cpu(int cpu)
>  	if (!stat->hash)
>  		return -ENOMEM;
>  
> -	if (!ftrace_profile_bits) {
> -		size--;
> -
> -		for (; size; size >>= 1)
> -			ftrace_profile_bits++;
> -	}
> -
>  	/* Preallocate the function profiling pages */
>  	if (ftrace_profile_pages_init(stat) < 0) {
>  		kfree(stat->hash);

[PATCH v2 3/3] ftrace: Get rid of ftrace_profile_bits

[Namhyung Kim]

From: Namhyung Kim <namhyung.kim@lge.com>

It seems that function profiler's hash size is fixed at 1024.  Add and
use FTRACE_PROFILE_HASH_BITS instead and update hash size macro.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 kernel/trace/ftrace.c | 15 ++++-----------
 1 file changed, 4 insertions(+), 11 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index d38ad7145f2f..78f4398cb608 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -486,7 +486,6 @@ struct ftrace_profile_stat {
 #define PROFILES_PER_PAGE					\
 	(PROFILE_RECORDS_SIZE / sizeof(struct ftrace_profile))
 
-static int ftrace_profile_bits __read_mostly;
 static int ftrace_profile_enabled __read_mostly;
 
 /* ftrace_profile_lock - synchronize the enable and disable of the profiler */
@@ -494,7 +493,8 @@ static DEFINE_MUTEX(ftrace_profile_lock);
 
 static DEFINE_PER_CPU(struct ftrace_profile_stat, ftrace_profile_stats);
 
-#define FTRACE_PROFILE_HASH_SIZE 1024 /* must be power of 2 */
+#define FTRACE_PROFILE_HASH_BITS 10
+#define FTRACE_PROFILE_HASH_SIZE (1 << FTRACE_PROFILE_HASH_BITS)
 
 static void *
 function_stat_next(void *v, int idx)
@@ -724,13 +724,6 @@ static int ftrace_profile_init_cpu(int cpu)
 	if (!stat->hash)
 		return -ENOMEM;
 
-	if (!ftrace_profile_bits) {
-		size--;
-
-		for (; size; size >>= 1)
-			ftrace_profile_bits++;
-	}
-
 	/* Preallocate the function profiling pages */
 	if (ftrace_profile_pages_init(stat) < 0) {
 		kfree(stat->hash);
@@ -764,7 +757,7 @@ ftrace_find_profiled_func(struct ftrace_profile_stat *stat, unsigned long ip)
 	struct hlist_node *n;
 	unsigned long key;
 
-	key = hash_long(ip, ftrace_profile_bits);
+	key = hash_long(ip, FTRACE_PROFILE_HASH_BITS);
 	hhd = &stat->hash[key];
 
 	if (hlist_empty(hhd))
@@ -783,7 +776,7 @@ static void ftrace_add_profile(struct ftrace_profile_stat *stat,
 {
 	unsigned long key;
 
-	key = hash_long(rec->ip, ftrace_profile_bits);
+	key = hash_long(rec->ip, FTRACE_PROFILE_HASH_BITS);
 	hlist_add_head_rcu(&rec->node, &stat->hash[key]);
 }
 
-- 
1.7.11.7

Re: [PATCH v2 3/3] ftrace: Get rid of ftrace_profile_bits

[Steven Rostedt]

On Wed, 2013-04-10 at 08:55 +0900, Namhyung Kim wrote:
> From: Namhyung Kim <namhyung.kim@lge.com>
> 
> It seems that function profiler's hash size is fixed at 1024.  Add and
> use FTRACE_PROFILE_HASH_BITS instead and update hash size macro.

Thanks! I'll queue it in my 3.10 branch.

-- Steve

> 
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> ---