| Message ID | 20190604174412.13324-1-yamada.masahiro@socionext.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | kobject: return -ENOSPC when add_uevent_var() fails | expand |
On Tue, Jun 4, 2019 at 8:00 PM Masahiro Yamada <yamada.masahiro@socionext.com> wrote: > > This function never attempts to allocate memory, so returning -ENOMEM > looks weird to me. And why is the "looks weird to me" a good enough reason for making changes like this? The existing behavior is known and documented AFAICS and is it really so confusing? > The reason of the failure is there is no more space > in the given kobj_uevent_env structure. > > No caller of this function relies on this functing returning a specific > error code, so just change it to return -ENOSPC. The intended change, > if any, is the error number displayed in log messages. > > Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> > --- > > lib/kobject_uevent.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c > index 7998affa45d4..5ffd44bf4aad 100644 > --- a/lib/kobject_uevent.c > +++ b/lib/kobject_uevent.c > @@ -647,7 +647,7 @@ EXPORT_SYMBOL_GPL(kobject_uevent); > * @env: environment buffer structure > * @format: printf format for the key=value pair > * > - * Returns 0 if environment variable was added successfully or -ENOMEM > + * Returns 0 if environment variable was added successfully or -ENOSPC > * if no space was available. > */ > int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...) > @@ -657,7 +657,7 @@ int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...) > > if (env->envp_idx >= ARRAY_SIZE(env->envp)) { > WARN(1, KERN_ERR "add_uevent_var: too many keys\n"); > - return -ENOMEM; > + return -ENOSPC; > } > > va_start(args, format); > @@ -668,7 +668,7 @@ int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...) > > if (len >= (sizeof(env->buf) - env->buflen)) { > WARN(1, KERN_ERR "add_uevent_var: buffer size too small\n"); > - return -ENOMEM; > + return -ENOSPC; > } > > env->envp[env->envp_idx++] = &env->buf[env->buflen]; > -- > 2.17.1 >
On Wed, Jun 5, 2019 at 5:53 AM Rafael J. Wysocki <rafael@kernel.org> wrote: > > On Tue, Jun 4, 2019 at 8:00 PM Masahiro Yamada > <yamada.masahiro@socionext.com> wrote: > > > > This function never attempts to allocate memory, so returning -ENOMEM > > looks weird to me. > > And why is the "looks weird to me" a good enough reason for making > changes like this? Since the code is read much more than written, this change eliminates the question of "why -ENOMEM here?" Masahiro Yamada > The existing behavior is known and documented AFAICS and is it really > so confusing? > > > The reason of the failure is there is no more space > > in the given kobj_uevent_env structure. > > > > No caller of this function relies on this functing returning a specific > > error code, so just change it to return -ENOSPC. The intended change, > > if any, is the error number displayed in log messages. > > > > Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> > > --- > > > > lib/kobject_uevent.c | 6 +++--- > > 1 file changed, 3 insertions(+), 3 deletions(-) > > > > diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c > > index 7998affa45d4..5ffd44bf4aad 100644 > > --- a/lib/kobject_uevent.c > > +++ b/lib/kobject_uevent.c > > @@ -647,7 +647,7 @@ EXPORT_SYMBOL_GPL(kobject_uevent); > > * @env: environment buffer structure > > * @format: printf format for the key=value pair > > * > > - * Returns 0 if environment variable was added successfully or -ENOMEM > > + * Returns 0 if environment variable was added successfully or -ENOSPC > > * if no space was available. > > */ > > int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...) > > @@ -657,7 +657,7 @@ int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...) > > > > if (env->envp_idx >= ARRAY_SIZE(env->envp)) { > > WARN(1, KERN_ERR "add_uevent_var: too many keys\n"); > > - return -ENOMEM; > > + return -ENOSPC; > > } > > > > va_start(args, format); > > @@ -668,7 +668,7 @@ int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...) > > > > if (len >= (sizeof(env->buf) - env->buflen)) { > > WARN(1, KERN_ERR "add_uevent_var: buffer size too small\n"); > > - return -ENOMEM; > > + return -ENOSPC; > > } > > > > env->envp[env->envp_idx++] = &env->buf[env->buflen]; > > -- > > 2.17.1
On Fri, Jun 7, 2019 at 2:02 PM Masahiro Yamada <yamada.masahiro@socionext.com> wrote: > > On Wed, Jun 5, 2019 at 5:53 AM Rafael J. Wysocki <rafael@kernel.org> wrote: > > > > On Tue, Jun 4, 2019 at 8:00 PM Masahiro Yamada > > <yamada.masahiro@socionext.com> wrote: > > > > > > This function never attempts to allocate memory, so returning -ENOMEM > > > looks weird to me. > > > > And why is the "looks weird to me" a good enough reason for making > > changes like this? > > > Since the code is read much more than written, > this change eliminates the question of "why -ENOMEM here?" And you are sure that nobody relies on the current return value?
On Wed, Jun 05, 2019 at 02:44:12AM +0900, Masahiro Yamada wrote: > This function never attempts to allocate memory, so returning -ENOMEM > looks weird to me. The reason of the failure is there is no more space > in the given kobj_uevent_env structure. > > No caller of this function relies on this functing returning a specific > error code, so just change it to return -ENOSPC. The intended change, > if any, is the error number displayed in log messages. > > Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> > --- > > lib/kobject_uevent.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c > index 7998affa45d4..5ffd44bf4aad 100644 > --- a/lib/kobject_uevent.c > +++ b/lib/kobject_uevent.c > @@ -647,7 +647,7 @@ EXPORT_SYMBOL_GPL(kobject_uevent); > * @env: environment buffer structure > * @format: printf format for the key=value pair > * > - * Returns 0 if environment variable was added successfully or -ENOMEM > + * Returns 0 if environment variable was added successfully or -ENOSPC > * if no space was available. > */ > int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...) > @@ -657,7 +657,7 @@ int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...) > > if (env->envp_idx >= ARRAY_SIZE(env->envp)) { > WARN(1, KERN_ERR "add_uevent_var: too many keys\n"); > - return -ENOMEM; > + return -ENOSPC; As Rafael says, changing this for no good reason is not a good idea, sorry. Let's live with it as-is unless you can show some place where this specific error value is causing problems. thanks, greg k-h
On Tue, Jun 11, 2019 at 2:47 AM Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote: > > On Wed, Jun 05, 2019 at 02:44:12AM +0900, Masahiro Yamada wrote: > > This function never attempts to allocate memory, so returning -ENOMEM > > looks weird to me. The reason of the failure is there is no more space > > in the given kobj_uevent_env structure. > > > > No caller of this function relies on this functing returning a specific > > error code, so just change it to return -ENOSPC. The intended change, > > if any, is the error number displayed in log messages. > > > > Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> > > --- > > > > lib/kobject_uevent.c | 6 +++--- > > 1 file changed, 3 insertions(+), 3 deletions(-) > > > > diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c > > index 7998affa45d4..5ffd44bf4aad 100644 > > --- a/lib/kobject_uevent.c > > +++ b/lib/kobject_uevent.c > > @@ -647,7 +647,7 @@ EXPORT_SYMBOL_GPL(kobject_uevent); > > * @env: environment buffer structure > > * @format: printf format for the key=value pair > > * > > - * Returns 0 if environment variable was added successfully or -ENOMEM > > + * Returns 0 if environment variable was added successfully or -ENOSPC > > * if no space was available. > > */ > > int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...) > > @@ -657,7 +657,7 @@ int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...) > > > > if (env->envp_idx >= ARRAY_SIZE(env->envp)) { > > WARN(1, KERN_ERR "add_uevent_var: too many keys\n"); > > - return -ENOMEM; > > + return -ENOSPC; > > As Rafael says, changing this for no good reason is not a good idea, > sorry. Let's live with it as-is unless you can show some place where > this specific error value is causing problems. Didn't you see WARN() above the return code? I rephrased the commit log for clarification in v2. Thanks. -- Best Regards Masahiro Yamada
On Tue, Jun 11, 2019 at 06:09:55AM +0900, Masahiro Yamada wrote: > On Tue, Jun 11, 2019 at 2:47 AM Greg Kroah-Hartman > <gregkh@linuxfoundation.org> wrote: > > > > On Wed, Jun 05, 2019 at 02:44:12AM +0900, Masahiro Yamada wrote: > > > This function never attempts to allocate memory, so returning -ENOMEM > > > looks weird to me. The reason of the failure is there is no more space > > > in the given kobj_uevent_env structure. > > > > > > No caller of this function relies on this functing returning a specific > > > error code, so just change it to return -ENOSPC. The intended change, > > > if any, is the error number displayed in log messages. > > > > > > Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> > > > --- > > > > > > lib/kobject_uevent.c | 6 +++--- > > > 1 file changed, 3 insertions(+), 3 deletions(-) > > > > > > diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c > > > index 7998affa45d4..5ffd44bf4aad 100644 > > > --- a/lib/kobject_uevent.c > > > +++ b/lib/kobject_uevent.c > > > @@ -647,7 +647,7 @@ EXPORT_SYMBOL_GPL(kobject_uevent); > > > * @env: environment buffer structure > > > * @format: printf format for the key=value pair > > > * > > > - * Returns 0 if environment variable was added successfully or -ENOMEM > > > + * Returns 0 if environment variable was added successfully or -ENOSPC > > > * if no space was available. > > > */ > > > int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...) > > > @@ -657,7 +657,7 @@ int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...) > > > > > > if (env->envp_idx >= ARRAY_SIZE(env->envp)) { > > > WARN(1, KERN_ERR "add_uevent_var: too many keys\n"); > > > - return -ENOMEM; > > > + return -ENOSPC; > > > > As Rafael says, changing this for no good reason is not a good idea, > > sorry. Let's live with it as-is unless you can show some place where > > this specific error value is causing problems. > > > > Didn't you see WARN() above the return code? Yes. > I rephrased the commit log for clarification in v2. It still doesn't matter :) thanks, greg k-h
diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c index 7998affa45d4..5ffd44bf4aad 100644 --- a/lib/kobject_uevent.c +++ b/lib/kobject_uevent.c @@ -647,7 +647,7 @@ EXPORT_SYMBOL_GPL(kobject_uevent); * @env: environment buffer structure * @format: printf format for the key=value pair * - * Returns 0 if environment variable was added successfully or -ENOMEM + * Returns 0 if environment variable was added successfully or -ENOSPC * if no space was available. */ int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...) @@ -657,7 +657,7 @@ int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...) if (env->envp_idx >= ARRAY_SIZE(env->envp)) { WARN(1, KERN_ERR "add_uevent_var: too many keys\n"); - return -ENOMEM; + return -ENOSPC; } va_start(args, format); @@ -668,7 +668,7 @@ int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...) if (len >= (sizeof(env->buf) - env->buflen)) { WARN(1, KERN_ERR "add_uevent_var: buffer size too small\n"); - return -ENOMEM; + return -ENOSPC; } env->envp[env->envp_idx++] = &env->buf[env->buflen];
This function never attempts to allocate memory, so returning -ENOMEM looks weird to me. The reason of the failure is there is no more space in the given kobj_uevent_env structure. No caller of this function relies on this functing returning a specific error code, so just change it to return -ENOSPC. The intended change, if any, is the error number displayed in log messages. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> --- lib/kobject_uevent.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) -- 2.17.1