| Message ID | 20240817025624.13157-7-laoar.shao@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Improve the copy of task comm | expand |
Hi Yafang, On Sat, Aug 17, 2024 at 10:56:22AM GMT, Yafang Shao wrote: > These three functions follow the same pattern. To deduplicate the code, > let's introduce a common helper __kmemdup_nul(). > > Suggested-by: Andrew Morton <akpm@linux-foundation.org> > Signed-off-by: Yafang Shao <laoar.shao@gmail.com> > Cc: Simon Horman <horms@kernel.org> > Cc: Matthew Wilcox <willy@infradead.org> > --- > mm/util.c | 67 +++++++++++++++++++++---------------------------------- > 1 file changed, 26 insertions(+), 41 deletions(-) > > diff --git a/mm/util.c b/mm/util.c > index 4542d8a800d9..310c7735c617 100644 > --- a/mm/util.c > +++ b/mm/util.c > @@ -45,33 +45,40 @@ void kfree_const(const void *x) > EXPORT_SYMBOL(kfree_const); > > /** > - * kstrdup - allocate space for and copy an existing string > - * @s: the string to duplicate > + * __kmemdup_nul - Create a NUL-terminated string from @s, which might be unterminated. > + * @s: The data to copy > + * @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 or %NULL in case of error > + * Return: newly allocated copy of @s with NUL-termination or %NULL in > + * case of error > */ > -noinline > -char *kstrdup(const char *s, gfp_t gfp) > +static __always_inline char *__kmemdup_nul(const char *s, size_t len, gfp_t gfp) > { > - size_t len; > char *buf; > > - if (!s) > + buf = kmalloc_track_caller(len, gfp); > + if (!buf) > 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'; > - } > + memcpy(buf, s, len); > + /* Ensure the buf is always NUL-terminated, regardless of @s. */ > + buf[len - 1] = '\0'; > return buf; > } > + > +/** > + * kstrdup - allocate space for and copy an existing string > + * @s: the string to duplicate > + * @gfp: the GFP mask used in the kmalloc() call when allocating memory > + * > + * Return: newly allocated copy of @s or %NULL in case of error > + */ > +noinline > +char *kstrdup(const char *s, gfp_t gfp) > +{ > + return s ? __kmemdup_nul(s, strlen(s) + 1, gfp) : NULL; > +} > EXPORT_SYMBOL(kstrdup); > > /** > @@ -106,19 +113,7 @@ EXPORT_SYMBOL(kstrdup_const); > */ > char *kstrndup(const char *s, size_t max, gfp_t gfp) > { > - size_t len; > - char *buf; > - > - if (!s) > - 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 s ? __kmemdup_nul(s, strnlen(s, max) + 1, gfp) : NULL; > } > EXPORT_SYMBOL(kstrndup); > > @@ -192,17 +187,7 @@ EXPORT_SYMBOL(kvmemdup); > */ > char *kmemdup_nul(const char *s, size_t len, gfp_t gfp) > { > - char *buf; > - > - if (!s) > - return NULL; > - > - buf = kmalloc_track_caller(len + 1, gfp); > - if (buf) { > - memcpy(buf, s, len); > - buf[len] = '\0'; > - } > - return buf; > + return s ? __kmemdup_nul(s, len + 1, gfp) : NULL; > } > EXPORT_SYMBOL(kmemdup_nul); I like the idea of the patch, but it's plagued with all those +1 and -1. I think that's due to a bad choice of value being passed by. If you pass the actual length of the string (as suggested in my reply to the previous patch) you should end up with a cleaner set of APIs. The only remaining +1 is for kmalloc_track_caller(), which I ignore what it does. char * __kmemdup_nul(const char *s, size_t len, gfp_t gfp) { char *buf; buf = kmalloc_track_caller(len + 1, gfp); if (!buf) return NULL; strcpy(mempcpy(buf, s, len), ""); return buf; } char * kstrdup(const char *s, gfp_t gfp) { return s ? __kmemdup_nul(s, strlen(s), gfp) : NULL; } char * kstrndup(const char *s, size_t n, gfp_t gfp) { return s ? __kmemdup_nul(s, strnlen(s, n), gfp) : NULL; } char * kmemdup_nul(const char *s, size_t len, gfp_t gfp) { return s ? __kmemdup_nul(s, len, gfp) : NULL; } Have a lovely day! Alex
On Sat, Aug 17, 2024 at 10:58:02AM GMT, Alejandro Colomar wrote: > Hi Yafang, > > On Sat, Aug 17, 2024 at 10:56:22AM GMT, Yafang Shao wrote: > > These three functions follow the same pattern. To deduplicate the code, > > let's introduce a common helper __kmemdup_nul(). > > > > Suggested-by: Andrew Morton <akpm@linux-foundation.org> > > Signed-off-by: Yafang Shao <laoar.shao@gmail.com> > > Cc: Simon Horman <horms@kernel.org> > > Cc: Matthew Wilcox <willy@infradead.org> > > --- > > mm/util.c | 67 +++++++++++++++++++++---------------------------------- > > 1 file changed, 26 insertions(+), 41 deletions(-) > > > > diff --git a/mm/util.c b/mm/util.c > > index 4542d8a800d9..310c7735c617 100644 > > --- a/mm/util.c > > +++ b/mm/util.c > > @@ -45,33 +45,40 @@ void kfree_const(const void *x) > > EXPORT_SYMBOL(kfree_const); > > > > /** > > - * kstrdup - allocate space for and copy an existing string > > - * @s: the string to duplicate > > + * __kmemdup_nul - Create a NUL-terminated string from @s, which might be unterminated. > > + * @s: The data to copy > > + * @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 or %NULL in case of error > > + * Return: newly allocated copy of @s with NUL-termination or %NULL in > > + * case of error > > */ > > -noinline > > -char *kstrdup(const char *s, gfp_t gfp) > > +static __always_inline char *__kmemdup_nul(const char *s, size_t len, gfp_t gfp) > > { > > - size_t len; > > char *buf; > > > > - if (!s) > > + buf = kmalloc_track_caller(len, gfp); > > + if (!buf) > > 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'; > > - } > > + memcpy(buf, s, len); > > + /* Ensure the buf is always NUL-terminated, regardless of @s. */ > > + buf[len - 1] = '\0'; > > return buf; > > } > > + > > +/** > > + * kstrdup - allocate space for and copy an existing string > > + * @s: the string to duplicate > > + * @gfp: the GFP mask used in the kmalloc() call when allocating memory > > + * > > + * Return: newly allocated copy of @s or %NULL in case of error > > + */ > > +noinline > > +char *kstrdup(const char *s, gfp_t gfp) > > +{ > > + return s ? __kmemdup_nul(s, strlen(s) + 1, gfp) : NULL; > > +} > > EXPORT_SYMBOL(kstrdup); > > > > /** > > @@ -106,19 +113,7 @@ EXPORT_SYMBOL(kstrdup_const); > > */ > > char *kstrndup(const char *s, size_t max, gfp_t gfp) > > { > > - size_t len; > > - char *buf; > > - > > - if (!s) > > - 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 s ? __kmemdup_nul(s, strnlen(s, max) + 1, gfp) : NULL; > > } > > EXPORT_SYMBOL(kstrndup); > > > > @@ -192,17 +187,7 @@ EXPORT_SYMBOL(kvmemdup); > > */ > > char *kmemdup_nul(const char *s, size_t len, gfp_t gfp) > > { > > - char *buf; > > - > > - if (!s) > > - return NULL; > > - > > - buf = kmalloc_track_caller(len + 1, gfp); > > - if (buf) { > > - memcpy(buf, s, len); > > - buf[len] = '\0'; > > - } > > - return buf; > > + return s ? __kmemdup_nul(s, len + 1, gfp) : NULL; > > } > > EXPORT_SYMBOL(kmemdup_nul); > > I like the idea of the patch, but it's plagued with all those +1 and -1. > I think that's due to a bad choice of value being passed by. If you > pass the actual length of the string (as suggested in my reply to the > previous patch) you should end up with a cleaner set of APIs. > > The only remaining +1 is for kmalloc_track_caller(), which I ignore what > it does. D'oh, of course that's the malloc. Yes, it makes sense to have a +1 there. > > char * > __kmemdup_nul(const char *s, size_t len, gfp_t gfp) > { > char *buf; > > buf = kmalloc_track_caller(len + 1, gfp); > if (!buf) > return NULL; > > strcpy(mempcpy(buf, s, len), ""); > return buf; Alternatively, you can also rewrite the above two lines into one as: return strncat(strcpy(buf, ""), s, len); The good thing is that you have strncat() in the kernel, AFAICS. I reminded myself when checking the definitions that I wrote in shadow: #define XSTRNDUP(s) \ ( \ STRNCAT(strcpy(XMALLOC(strnlen(s, NITEMS(s)) + 1, char), ""), s) \ ) #define STRNDUPA(s) \ ( \ STRNCAT(strcpy(alloca(strnlen(s, NITEMS(s)) + 1), ""), s) \ ) Cheers, Alex > } > > char * > kstrdup(const char *s, gfp_t gfp) > { > return s ? __kmemdup_nul(s, strlen(s), gfp) : NULL; > } > > char * > kstrndup(const char *s, size_t n, gfp_t gfp) > { > return s ? __kmemdup_nul(s, strnlen(s, n), gfp) : NULL; > } > > char * > kmemdup_nul(const char *s, size_t len, gfp_t gfp) > { > return s ? __kmemdup_nul(s, len, gfp) : NULL; > } > > Have a lovely day! > Alex > > -- > <https://www.alejandro-colomar.es/>
Hi Yafang, On Sat, Aug 17, 2024 at 10:58:02AM GMT, Alejandro Colomar wrote: > Hi Yafang, > > On Sat, Aug 17, 2024 at 10:56:22AM GMT, Yafang Shao wrote: > > These three functions follow the same pattern. To deduplicate the code, > > let's introduce a common helper __kmemdup_nul(). > > > > Suggested-by: Andrew Morton <akpm@linux-foundation.org> > > Signed-off-by: Yafang Shao <laoar.shao@gmail.com> > > Cc: Simon Horman <horms@kernel.org> > > Cc: Matthew Wilcox <willy@infradead.org> > > --- > > mm/util.c | 67 +++++++++++++++++++++---------------------------------- > > 1 file changed, 26 insertions(+), 41 deletions(-) > > > > diff --git a/mm/util.c b/mm/util.c > > index 4542d8a800d9..310c7735c617 100644 > > --- a/mm/util.c > > +++ b/mm/util.c > > @@ -45,33 +45,40 @@ void kfree_const(const void *x) > > EXPORT_SYMBOL(kfree_const); > > > > /** > > - * kstrdup - allocate space for and copy an existing string > > - * @s: the string to duplicate > > + * __kmemdup_nul - Create a NUL-terminated string from @s, which might be unterminated. > > + * @s: The data to copy > > + * @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 or %NULL in case of error > > + * Return: newly allocated copy of @s with NUL-termination or %NULL in > > + * case of error > > */ > > -noinline > > -char *kstrdup(const char *s, gfp_t gfp) > > +static __always_inline char *__kmemdup_nul(const char *s, size_t len, gfp_t gfp) > > { > > - size_t len; > > char *buf; > > > > - if (!s) > > + buf = kmalloc_track_caller(len, gfp); > > + if (!buf) > > 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'; > > - } > > + memcpy(buf, s, len); > > + /* Ensure the buf is always NUL-terminated, regardless of @s. */ > > + buf[len - 1] = '\0'; > > return buf; > > } > > + > > +/** > > + * kstrdup - allocate space for and copy an existing string > > + * @s: the string to duplicate > > + * @gfp: the GFP mask used in the kmalloc() call when allocating memory > > + * > > + * Return: newly allocated copy of @s or %NULL in case of error > > + */ > > +noinline > > +char *kstrdup(const char *s, gfp_t gfp) > > +{ > > + return s ? __kmemdup_nul(s, strlen(s) + 1, gfp) : NULL; > > +} > > EXPORT_SYMBOL(kstrdup); > > > > /** > > @@ -106,19 +113,7 @@ EXPORT_SYMBOL(kstrdup_const); > > */ > > char *kstrndup(const char *s, size_t max, gfp_t gfp) > > { > > - size_t len; > > - char *buf; > > - > > - if (!s) > > - 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 s ? __kmemdup_nul(s, strnlen(s, max) + 1, gfp) : NULL; > > } > > EXPORT_SYMBOL(kstrndup); > > > > @@ -192,17 +187,7 @@ EXPORT_SYMBOL(kvmemdup); > > */ > > char *kmemdup_nul(const char *s, size_t len, gfp_t gfp) > > { > > - char *buf; > > - > > - if (!s) > > - return NULL; > > - > > - buf = kmalloc_track_caller(len + 1, gfp); > > - if (buf) { > > - memcpy(buf, s, len); > > - buf[len] = '\0'; > > - } > > - return buf; > > + return s ? __kmemdup_nul(s, len + 1, gfp) : NULL; > > } > > EXPORT_SYMBOL(kmemdup_nul); > > I like the idea of the patch, but it's plagued with all those +1 and -1. > I think that's due to a bad choice of value being passed by. If you > pass the actual length of the string (as suggested in my reply to the > previous patch) you should end up with a cleaner set of APIs. > > The only remaining +1 is for kmalloc_track_caller(), which I ignore what > it does. > > char * > __kmemdup_nul(const char *s, size_t len, gfp_t gfp) > { > char *buf; > > buf = kmalloc_track_caller(len + 1, gfp); > if (!buf) > return NULL; > > strcpy(mempcpy(buf, s, len), ""); Changing these strcpy(, "") to the usual; ='\0' or =0, but I'd still recommend the rest of the changes, that is, changing the value passed in len, to remove several +1 and -1s. What do you think? Have a lovely day! Alex > return buf; > } > > char * > kstrdup(const char *s, gfp_t gfp) > { > return s ? __kmemdup_nul(s, strlen(s), gfp) : NULL; > } > > char * > kstrndup(const char *s, size_t n, gfp_t gfp) > { > return s ? __kmemdup_nul(s, strnlen(s, n), gfp) : NULL; > } > > char * > kmemdup_nul(const char *s, size_t len, gfp_t gfp) > { > return s ? __kmemdup_nul(s, len, gfp) : NULL; > } > > Have a lovely day! > Alex > > -- > <https://www.alejandro-colomar.es/>
On Mon, Aug 26, 2024 at 5:25 PM Alejandro Colomar <alx@kernel.org> wrote: > > Hi Yafang, > > On Sat, Aug 17, 2024 at 10:58:02AM GMT, Alejandro Colomar wrote: > > Hi Yafang, > > > > On Sat, Aug 17, 2024 at 10:56:22AM GMT, Yafang Shao wrote: > > > These three functions follow the same pattern. To deduplicate the code, > > > let's introduce a common helper __kmemdup_nul(). > > > > > > Suggested-by: Andrew Morton <akpm@linux-foundation.org> > > > Signed-off-by: Yafang Shao <laoar.shao@gmail.com> > > > Cc: Simon Horman <horms@kernel.org> > > > Cc: Matthew Wilcox <willy@infradead.org> > > > --- > > > mm/util.c | 67 +++++++++++++++++++++---------------------------------- > > > 1 file changed, 26 insertions(+), 41 deletions(-) > > > > > > diff --git a/mm/util.c b/mm/util.c > > > index 4542d8a800d9..310c7735c617 100644 > > > --- a/mm/util.c > > > +++ b/mm/util.c > > > @@ -45,33 +45,40 @@ void kfree_const(const void *x) > > > EXPORT_SYMBOL(kfree_const); > > > > > > /** > > > - * kstrdup - allocate space for and copy an existing string > > > - * @s: the string to duplicate > > > + * __kmemdup_nul - Create a NUL-terminated string from @s, which might be unterminated. > > > + * @s: The data to copy > > > + * @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 or %NULL in case of error > > > + * Return: newly allocated copy of @s with NUL-termination or %NULL in > > > + * case of error > > > */ > > > -noinline > > > -char *kstrdup(const char *s, gfp_t gfp) > > > +static __always_inline char *__kmemdup_nul(const char *s, size_t len, gfp_t gfp) > > > { > > > - size_t len; > > > char *buf; > > > > > > - if (!s) > > > + buf = kmalloc_track_caller(len, gfp); > > > + if (!buf) > > > 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'; > > > - } > > > + memcpy(buf, s, len); > > > + /* Ensure the buf is always NUL-terminated, regardless of @s. */ > > > + buf[len - 1] = '\0'; > > > return buf; > > > } > > > + > > > +/** > > > + * kstrdup - allocate space for and copy an existing string > > > + * @s: the string to duplicate > > > + * @gfp: the GFP mask used in the kmalloc() call when allocating memory > > > + * > > > + * Return: newly allocated copy of @s or %NULL in case of error > > > + */ > > > +noinline > > > +char *kstrdup(const char *s, gfp_t gfp) > > > +{ > > > + return s ? __kmemdup_nul(s, strlen(s) + 1, gfp) : NULL; > > > +} > > > EXPORT_SYMBOL(kstrdup); > > > > > > /** > > > @@ -106,19 +113,7 @@ EXPORT_SYMBOL(kstrdup_const); > > > */ > > > char *kstrndup(const char *s, size_t max, gfp_t gfp) > > > { > > > - size_t len; > > > - char *buf; > > > - > > > - if (!s) > > > - 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 s ? __kmemdup_nul(s, strnlen(s, max) + 1, gfp) : NULL; > > > } > > > EXPORT_SYMBOL(kstrndup); > > > > > > @@ -192,17 +187,7 @@ EXPORT_SYMBOL(kvmemdup); > > > */ > > > char *kmemdup_nul(const char *s, size_t len, gfp_t gfp) > > > { > > > - char *buf; > > > - > > > - if (!s) > > > - return NULL; > > > - > > > - buf = kmalloc_track_caller(len + 1, gfp); > > > - if (buf) { > > > - memcpy(buf, s, len); > > > - buf[len] = '\0'; > > > - } > > > - return buf; > > > + return s ? __kmemdup_nul(s, len + 1, gfp) : NULL; > > > } > > > EXPORT_SYMBOL(kmemdup_nul); > > > > I like the idea of the patch, but it's plagued with all those +1 and -1. > > I think that's due to a bad choice of value being passed by. If you > > pass the actual length of the string (as suggested in my reply to the > > previous patch) you should end up with a cleaner set of APIs. > > > > The only remaining +1 is for kmalloc_track_caller(), which I ignore what > > it does. > > > > char * > > __kmemdup_nul(const char *s, size_t len, gfp_t gfp) > > { > > char *buf; > > > > buf = kmalloc_track_caller(len + 1, gfp); > > if (!buf) > > return NULL; > > > > strcpy(mempcpy(buf, s, len), ""); > > Changing these strcpy(, "") to the usual; ='\0' or =0, but I'd still > recommend the rest of the changes, that is, changing the value passed in > len, to remove several +1 and -1s. > > What do you think? I will update it. Thanks for your suggestion.
diff --git a/mm/util.c b/mm/util.c index 4542d8a800d9..310c7735c617 100644 --- a/mm/util.c +++ b/mm/util.c @@ -45,33 +45,40 @@ void kfree_const(const void *x) EXPORT_SYMBOL(kfree_const); /** - * kstrdup - allocate space for and copy an existing string - * @s: the string to duplicate + * __kmemdup_nul - Create a NUL-terminated string from @s, which might be unterminated. + * @s: The data to copy + * @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 or %NULL in case of error + * Return: newly allocated copy of @s with NUL-termination or %NULL in + * case of error */ -noinline -char *kstrdup(const char *s, gfp_t gfp) +static __always_inline char *__kmemdup_nul(const char *s, size_t len, gfp_t gfp) { - size_t len; char *buf; - if (!s) + buf = kmalloc_track_caller(len, gfp); + if (!buf) 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'; - } + memcpy(buf, s, len); + /* Ensure the buf is always NUL-terminated, regardless of @s. */ + buf[len - 1] = '\0'; return buf; } + +/** + * kstrdup - allocate space for and copy an existing string + * @s: the string to duplicate + * @gfp: the GFP mask used in the kmalloc() call when allocating memory + * + * Return: newly allocated copy of @s or %NULL in case of error + */ +noinline +char *kstrdup(const char *s, gfp_t gfp) +{ + return s ? __kmemdup_nul(s, strlen(s) + 1, gfp) : NULL; +} EXPORT_SYMBOL(kstrdup); /** @@ -106,19 +113,7 @@ EXPORT_SYMBOL(kstrdup_const); */ char *kstrndup(const char *s, size_t max, gfp_t gfp) { - size_t len; - char *buf; - - if (!s) - 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 s ? __kmemdup_nul(s, strnlen(s, max) + 1, gfp) : NULL; } EXPORT_SYMBOL(kstrndup); @@ -192,17 +187,7 @@ EXPORT_SYMBOL(kvmemdup); */ char *kmemdup_nul(const char *s, size_t len, gfp_t gfp) { - char *buf; - - if (!s) - return NULL; - - buf = kmalloc_track_caller(len + 1, gfp); - if (buf) { - memcpy(buf, s, len); - buf[len] = '\0'; - } - return buf; + return s ? __kmemdup_nul(s, len + 1, gfp) : NULL; } EXPORT_SYMBOL(kmemdup_nul);
These three functions follow the same pattern. To deduplicate the code, let's introduce a common helper __kmemdup_nul(). Suggested-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Yafang Shao <laoar.shao@gmail.com> Cc: Simon Horman <horms@kernel.org> Cc: Matthew Wilcox <willy@infradead.org> --- mm/util.c | 67 +++++++++++++++++++++---------------------------------- 1 file changed, 26 insertions(+), 41 deletions(-)