| Message ID | 20240621022959.9124-7-laoar.shao@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Improve the copy of task comm | expand |
On Fri, Jun 21, 2024 at 10:29:54AM +0800, Yafang Shao wrote: > These three functions follow the same pattern. To deduplicate the code, > let's introduce a common help __kstrndup(). > > Suggested-by: Andrew Morton <akpm@linux-foundation.org> > Signed-off-by: Yafang Shao <laoar.shao@gmail.com> Hi Yafang Shao, Some minor nits from my side. > --- > mm/internal.h | 24 ++++++++++++++++++++++++ > mm/util.c | 27 ++++----------------------- > 2 files changed, 28 insertions(+), 23 deletions(-) > > diff --git a/mm/internal.h b/mm/internal.h > index b2c75b12014e..fd87f685739b 100644 > --- a/mm/internal.h > +++ b/mm/internal.h > @@ -1521,4 +1521,28 @@ static inline void shrinker_debugfs_remove(struct dentry *debugfs_entry, > void workingset_update_node(struct xa_node *node); > extern struct list_lru shadow_nodes; > > +/** > + * __kstrndup - Create a NUL-terminated string from @s, which might be unterminated. > + * @s: The data to stringify > + * @len: The size of the data, including the null terminator > + * @gfp: the GFP mask used in the kmalloc() call when allocating memory > + * > + * Return: newly allocated copy of @s with NUL-termination or %NULL in > + * case of error > + */ > +static __always_inline char *__kstrndup(const char *s, size_t len, gfp_t gfp) > +{ > + char *buf; > + > + buf = kmalloc_track_caller(len, gfp); > + if (!buf) > + return NULL; > + > + memcpy(buf, s, len); > + /* Ensure the buf is always NUL-terminated, regardless of @s. */ > + buf[len - 1] = '\0'; > + return buf; > +} > + > + nit: One blank line is enough. > #endif /* __MM_INTERNAL_H */ > diff --git a/mm/util.c b/mm/util.c > index 41c7875572ed..d9135c5fdf7f 100644 > --- a/mm/util.c > +++ b/mm/util.c > @@ -58,17 +58,8 @@ char *kstrdup(const char *s, gfp_t gfp) > if (!s) > return NULL; > > - len = strlen(s) + 1; > - buf = kmalloc_track_caller(len, gfp); > - if (buf) { > - memcpy(buf, s, len); > - /* During memcpy(), the string might be updated to a new value, > - * which could be longer than the string when strlen() is > - * called. Therefore, we need to add a null termimator. > - */ > - buf[len - 1] = '\0'; > - } > - return buf; nit: The local variable buf is now unused, and should be removed from kstrdup(). Likewise for kstrndup() and kmemdup_nul() Flagged by W=1 builds with gcc-13 and clang-18, and Smatch. > + len = strlen(s); > + return __kstrndup(s, len + 1, gfp); > } > EXPORT_SYMBOL(kstrdup); > > @@ -111,12 +102,7 @@ char *kstrndup(const char *s, size_t max, gfp_t gfp) > return NULL; > > len = strnlen(s, max); > - buf = kmalloc_track_caller(len+1, gfp); > - if (buf) { > - memcpy(buf, s, len); > - buf[len] = '\0'; > - } > - return buf; > + return __kstrndup(s, len + 1, gfp); > } > EXPORT_SYMBOL(kstrndup); > > @@ -195,12 +181,7 @@ char *kmemdup_nul(const char *s, size_t len, gfp_t gfp) > if (!s) > return NULL; > > - buf = kmalloc_track_caller(len + 1, gfp); > - if (buf) { > - memcpy(buf, s, len); > - buf[len] = '\0'; > - } > - return buf; > + return __kstrndup(s, len + 1, gfp); > } > EXPORT_SYMBOL(kmemdup_nul); > > -- > 2.39.1 > >
On Fri, Jun 21, 2024 at 10:29:54AM +0800, Yafang Shao wrote:
> +++ b/mm/internal.h
Why are you putting __kstrndup in a header file when it's only used
in util.c?
Also, I think this function is actually __kmemdup_nul(), not
__kstrndup().
On Fri, Jun 21, 2024 at 9:51 PM Simon Horman <horms@kernel.org> wrote: > > On Fri, Jun 21, 2024 at 10:29:54AM +0800, Yafang Shao wrote: > > These three functions follow the same pattern. To deduplicate the code, > > let's introduce a common help __kstrndup(). > > > > Suggested-by: Andrew Morton <akpm@linux-foundation.org> > > Signed-off-by: Yafang Shao <laoar.shao@gmail.com> > > Hi Yafang Shao, > > Some minor nits from my side. > > > --- > > mm/internal.h | 24 ++++++++++++++++++++++++ > > mm/util.c | 27 ++++----------------------- > > 2 files changed, 28 insertions(+), 23 deletions(-) > > > > diff --git a/mm/internal.h b/mm/internal.h > > index b2c75b12014e..fd87f685739b 100644 > > --- a/mm/internal.h > > +++ b/mm/internal.h > > @@ -1521,4 +1521,28 @@ static inline void shrinker_debugfs_remove(struct dentry *debugfs_entry, > > void workingset_update_node(struct xa_node *node); > > extern struct list_lru shadow_nodes; > > > > +/** > > + * __kstrndup - Create a NUL-terminated string from @s, which might be unterminated. > > + * @s: The data to stringify > > + * @len: The size of the data, including the null terminator > > + * @gfp: the GFP mask used in the kmalloc() call when allocating memory > > + * > > + * Return: newly allocated copy of @s with NUL-termination or %NULL in > > + * case of error > > + */ > > +static __always_inline char *__kstrndup(const char *s, size_t len, gfp_t gfp) > > +{ > > + char *buf; > > + > > + buf = kmalloc_track_caller(len, gfp); > > + if (!buf) > > + return NULL; > > + > > + memcpy(buf, s, len); > > + /* Ensure the buf is always NUL-terminated, regardless of @s. */ > > + buf[len - 1] = '\0'; > > + return buf; > > +} > > + > > + > > nit: One blank line is enough. Ah, will change it. > > > #endif /* __MM_INTERNAL_H */ > > diff --git a/mm/util.c b/mm/util.c > > index 41c7875572ed..d9135c5fdf7f 100644 > > --- a/mm/util.c > > +++ b/mm/util.c > > @@ -58,17 +58,8 @@ char *kstrdup(const char *s, gfp_t gfp) > > if (!s) > > return NULL; > > > > - len = strlen(s) + 1; > > - buf = kmalloc_track_caller(len, gfp); > > - if (buf) { > > - memcpy(buf, s, len); > > - /* During memcpy(), the string might be updated to a new value, > > - * which could be longer than the string when strlen() is > > - * called. Therefore, we need to add a null termimator. > > - */ > > - buf[len - 1] = '\0'; > > - } > > - return buf; > > nit: The local variable buf is now unused, and should be removed from kstrdup(). > Likewise for kstrndup() and kmemdup_nul() > > Flagged by W=1 builds with gcc-13 and clang-18, and Smatch. I missed that. Thanks for pointing it out.
On Fri, Jun 21, 2024 at 9:57 PM Matthew Wilcox <willy@infradead.org> wrote: > > On Fri, Jun 21, 2024 at 10:29:54AM +0800, Yafang Shao wrote: > > +++ b/mm/internal.h > > Why are you putting __kstrndup in a header file when it's only used > in util.c? I want to make it always inlined. However, it is not recommended to define an inline function in a .c file, right ? > > Also, I think this function is actually __kmemdup_nul(), not > __kstrndup(). > Good suggestion. Will use __kmemdup_nul() instead.
On Sun, Jun 23, 2024 at 10:29:30AM +0800, Yafang Shao wrote: > On Fri, Jun 21, 2024 at 9:57 PM Matthew Wilcox <willy@infradead.org> wrote: > > > > On Fri, Jun 21, 2024 at 10:29:54AM +0800, Yafang Shao wrote: > > > +++ b/mm/internal.h > > > > Why are you putting __kstrndup in a header file when it's only used > > in util.c? > > I want to make it always inlined. However, it is not recommended to > define an inline function in a .c file, right ? I'm not aware of any such recommendation. Better than putting it in a .h file that everybody has to look at but nobody uses.
On Sun, Jun 23, 2024 at 11:11 AM Matthew Wilcox <willy@infradead.org> wrote: > > On Sun, Jun 23, 2024 at 10:29:30AM +0800, Yafang Shao wrote: > > On Fri, Jun 21, 2024 at 9:57 PM Matthew Wilcox <willy@infradead.org> wrote: > > > > > > On Fri, Jun 21, 2024 at 10:29:54AM +0800, Yafang Shao wrote: > > > > +++ b/mm/internal.h > > > > > > Why are you putting __kstrndup in a header file when it's only used > > > in util.c? > > > > I want to make it always inlined. However, it is not recommended to > > define an inline function in a .c file, right ? > > I'm not aware of any such recommendation. Better than putting it in > a .h file that everybody has to look at but nobody uses. Understood. Will change it.
diff --git a/mm/internal.h b/mm/internal.h index b2c75b12014e..fd87f685739b 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -1521,4 +1521,28 @@ static inline void shrinker_debugfs_remove(struct dentry *debugfs_entry, void workingset_update_node(struct xa_node *node); extern struct list_lru shadow_nodes; +/** + * __kstrndup - Create a NUL-terminated string from @s, which might be unterminated. + * @s: The data to stringify + * @len: The size of the data, including the null terminator + * @gfp: the GFP mask used in the kmalloc() call when allocating memory + * + * Return: newly allocated copy of @s with NUL-termination or %NULL in + * case of error + */ +static __always_inline char *__kstrndup(const char *s, size_t len, gfp_t gfp) +{ + char *buf; + + buf = kmalloc_track_caller(len, gfp); + if (!buf) + return NULL; + + memcpy(buf, s, len); + /* Ensure the buf is always NUL-terminated, regardless of @s. */ + buf[len - 1] = '\0'; + return buf; +} + + #endif /* __MM_INTERNAL_H */ diff --git a/mm/util.c b/mm/util.c index 41c7875572ed..d9135c5fdf7f 100644 --- a/mm/util.c +++ b/mm/util.c @@ -58,17 +58,8 @@ char *kstrdup(const char *s, gfp_t gfp) if (!s) return NULL; - len = strlen(s) + 1; - buf = kmalloc_track_caller(len, gfp); - if (buf) { - memcpy(buf, s, len); - /* During memcpy(), the string might be updated to a new value, - * which could be longer than the string when strlen() is - * called. Therefore, we need to add a null termimator. - */ - buf[len - 1] = '\0'; - } - return buf; + len = strlen(s); + return __kstrndup(s, len + 1, gfp); } EXPORT_SYMBOL(kstrdup); @@ -111,12 +102,7 @@ char *kstrndup(const char *s, size_t max, gfp_t gfp) return NULL; len = strnlen(s, max); - buf = kmalloc_track_caller(len+1, gfp); - if (buf) { - memcpy(buf, s, len); - buf[len] = '\0'; - } - return buf; + return __kstrndup(s, len + 1, gfp); } EXPORT_SYMBOL(kstrndup); @@ -195,12 +181,7 @@ char *kmemdup_nul(const char *s, size_t len, gfp_t gfp) if (!s) return NULL; - buf = kmalloc_track_caller(len + 1, gfp); - if (buf) { - memcpy(buf, s, len); - buf[len] = '\0'; - } - return buf; + return __kstrndup(s, len + 1, gfp); } EXPORT_SYMBOL(kmemdup_nul);
These three functions follow the same pattern. To deduplicate the code, let's introduce a common help __kstrndup(). Suggested-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Yafang Shao <laoar.shao@gmail.com> --- mm/internal.h | 24 ++++++++++++++++++++++++ mm/util.c | 27 ++++----------------------- 2 files changed, 28 insertions(+), 23 deletions(-)