We should initialize the module dynamic debug datastructures
only after determining that the module is not loaded yet. This
fixes a bug that introduced in 2.6.35-rc2, where when a trying
to load a module twice, we also load it's dynamic printing data
twice which causes all sorts of nasty issues. Also handle
the dynamic debug cleanup later on failure.
Signed-off-by: Yehuda Sadeh <[email protected]>
---
include/linux/dynamic_debug.h | 4 ++--
kernel/module.c | 25 +++++++++++++++++--------
lib/dynamic_debug.c | 2 +-
3 files changed, 20 insertions(+), 11 deletions(-)
diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index b3cd4de..52c0da4 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -40,7 +40,7 @@ int ddebug_add_module(struct _ddebug *tab, unsigned int n,
const char *modname);
#if defined(CONFIG_DYNAMIC_DEBUG)
-extern int ddebug_remove_module(char *mod_name);
+extern int ddebug_remove_module(const char *mod_name);
#define __dynamic_dbg_enabled(dd) ({ \
int __ret = 0; \
@@ -73,7 +73,7 @@ extern int ddebug_remove_module(char *mod_name);
#else
-static inline int ddebug_remove_module(char *mod)
+static inline int ddebug_remove_module(const char *mod)
{
return 0;
}
diff --git a/kernel/module.c b/kernel/module.c
index 8c6b428..4b98b48 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2062,6 +2062,14 @@ static void dynamic_debug_setup(struct _ddebug *debug, unsigned int num)
#endif
}
+static void dynamic_debug_remove(struct _ddebug *debug)
+{
+#ifdef CONFIG_DYNAMIC_DEBUG
+ if (debug)
+ ddebug_remove_module(debug->modname);
+#endif
+}
+
static void *module_alloc_update_bounds(unsigned long size)
{
void *ret = module_alloc(size);
@@ -2124,6 +2132,8 @@ static noinline struct module *load_module(void __user *umod,
void *ptr = NULL; /* Stops spurious gcc warning */
unsigned long symoffs, stroffs, *strmap;
void __percpu *percpu;
+ struct _ddebug *debug = NULL;
+ unsigned int num_debug = 0;
mm_segment_t old_fs;
@@ -2476,15 +2486,9 @@ static noinline struct module *load_module(void __user *umod,
kfree(strmap);
strmap = NULL;
- if (!mod->taints) {
- struct _ddebug *debug;
- unsigned int num_debug;
-
+ if (!mod->taints)
debug = section_objs(hdr, sechdrs, secstrings, "__verbose",
sizeof(*debug), &num_debug);
- if (debug)
- dynamic_debug_setup(debug, num_debug);
- }
err = module_finalize(hdr, sechdrs, mod);
if (err < 0)
@@ -2526,10 +2530,13 @@ static noinline struct module *load_module(void __user *umod,
goto unlock;
}
+ if (debug)
+ dynamic_debug_setup(debug, num_debug);
+
/* Find duplicate symbols */
err = verify_export_symbols(mod);
if (err < 0)
- goto unlock;
+ goto ddebug;
list_add_rcu(&mod->list, &modules);
mutex_unlock(&module_mutex);
@@ -2557,6 +2564,8 @@ static noinline struct module *load_module(void __user *umod,
mutex_lock(&module_mutex);
/* Unlink carefully: kallsyms could be walking list. */
list_del_rcu(&mod->list);
+ ddebug:
+ dynamic_debug_remove(debug);
unlock:
mutex_unlock(&module_mutex);
synchronize_sched();
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 3df8eb1..02afc25 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -692,7 +692,7 @@ static void ddebug_table_free(struct ddebug_table *dt)
* Called in response to a module being unloaded. Removes
* any ddebug_table's which point at the module.
*/
-int ddebug_remove_module(char *mod_name)
+int ddebug_remove_module(const char *mod_name)
{
struct ddebug_table *dt, *nextdt;
int ret = -ENOENT;
--
1.5.6.5
On Wed, 16 Jun 2010 09:56:37 am Yehuda Sadeh wrote:
> We should initialize the module dynamic debug datastructures
> only after determining that the module is not loaded yet. This
> fixes a bug that introduced in 2.6.35-rc2, where when a trying
> to load a module twice, we also load it's dynamic printing data
> twice which causes all sorts of nasty issues. Also handle
> the dynamic debug cleanup later on failure.
>
> Signed-off-by: Yehuda Sadeh <[email protected]>
Hi Yehuda,
Thanks for tracking this down. One minor comment:
> #if defined(CONFIG_DYNAMIC_DEBUG)
> -extern int ddebug_remove_module(char *mod_name);
> +extern int ddebug_remove_module(const char *mod_name);
>
> #define __dynamic_dbg_enabled(dd) ({ \
> int __ret = 0; \
> @@ -73,7 +73,7 @@ extern int ddebug_remove_module(char *mod_name);
>
> #else
>
> -static inline int ddebug_remove_module(char *mod)
> +static inline int ddebug_remove_module(const char *mod)
> {
> return 0;
> }
This implies we don't need the #ifdef here:
> +static void dynamic_debug_remove(struct _ddebug *debug)
> +{
> +#ifdef CONFIG_DYNAMIC_DEBUG
> + if (debug)
> + ddebug_remove_module(debug->modname);
> +#endif
> +}
> +
So I removed it. It'd be nice to have a similar wrapper in the header
for ddebug_add_module so we can avoid the #ifdef there too, but that's
a separate patch.
Applied!
Rusty.
From: Yehuda Sadeh <[email protected]>
We should initialize the module dynamic debug datastructures
only after determining that the module is not loaded yet. This
fixes a bug that introduced in 2.6.35-rc2, where when a trying
to load a module twice, we also load it's dynamic printing data
twice which causes all sorts of nasty issues. Also handle
the dynamic debug cleanup later on failure.
Signed-off-by: Yehuda Sadeh <[email protected]>
Signed-off-by: Rusty Russell <[email protected]> (removed a #ifdef)
---
include/linux/dynamic_debug.h | 4 ++--
kernel/module.c | 23 +++++++++++++++--------
lib/dynamic_debug.c | 2 +-
3 files changed, 18 insertions(+), 11 deletions(-)
diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -40,7 +40,7 @@ int ddebug_add_module(struct _ddebug *ta
const char *modname);
#if defined(CONFIG_DYNAMIC_DEBUG)
-extern int ddebug_remove_module(char *mod_name);
+extern int ddebug_remove_module(const char *mod_name);
#define __dynamic_dbg_enabled(dd) ({ \
int __ret = 0; \
@@ -73,7 +73,7 @@ extern int ddebug_remove_module(char *mo
#else
-static inline int ddebug_remove_module(char *mod)
+static inline int ddebug_remove_module(const char *mod)
{
return 0;
}
diff --git a/kernel/module.c b/kernel/module.c
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2062,6 +2062,12 @@ static void dynamic_debug_setup(struct _
#endif
}
+static void dynamic_debug_remove(struct _ddebug *debug)
+{
+ if (debug)
+ ddebug_remove_module(debug->modname);
+}
+
static void *module_alloc_update_bounds(unsigned long size)
{
void *ret = module_alloc(size);
@@ -2124,6 +2130,8 @@ static noinline struct module *load_modu
void *ptr = NULL; /* Stops spurious gcc warning */
unsigned long symoffs, stroffs, *strmap;
void __percpu *percpu;
+ struct _ddebug *debug = NULL;
+ unsigned int num_debug = 0;
mm_segment_t old_fs;
@@ -2476,15 +2484,9 @@ static noinline struct module *load_modu
kfree(strmap);
strmap = NULL;
- if (!mod->taints) {
- struct _ddebug *debug;
- unsigned int num_debug;
-
+ if (!mod->taints)
debug = section_objs(hdr, sechdrs, secstrings, "__verbose",
sizeof(*debug), &num_debug);
- if (debug)
- dynamic_debug_setup(debug, num_debug);
- }
err = module_finalize(hdr, sechdrs, mod);
if (err < 0)
@@ -2526,10 +2528,13 @@ static noinline struct module *load_modu
goto unlock;
}
+ if (debug)
+ dynamic_debug_setup(debug, num_debug);
+
/* Find duplicate symbols */
err = verify_export_symbols(mod);
if (err < 0)
- goto unlock;
+ goto ddebug;
list_add_rcu(&mod->list, &modules);
mutex_unlock(&module_mutex);
@@ -2557,6 +2562,8 @@ static noinline struct module *load_modu
mutex_lock(&module_mutex);
/* Unlink carefully: kallsyms could be walking list. */
list_del_rcu(&mod->list);
+ ddebug:
+ dynamic_debug_remove(debug);
unlock:
mutex_unlock(&module_mutex);
synchronize_sched();
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -692,7 +692,7 @@ static void ddebug_table_free(struct dde
* Called in response to a module being unloaded. Removes
* any ddebug_table's which point at the module.
*/
-int ddebug_remove_module(char *mod_name)
+int ddebug_remove_module(const char *mod_name)
{
struct ddebug_table *dt, *nextdt;
int ret = -ENOENT;