Re: [PATCH] iwlwifi: pcie: make array prop static, shrinks object size

Greg Kroah-Hartman
2018-06-11T20:45:06Z

On Mon, Jun 11, 2018 at 12:40:55PM -0700, Joe Perches wrote:
> (adding Greg KH)
>
> On Mon, 2018-06-11 at 18:15 +0100, Colin King wrote:
> > From: Colin Ian King <colin.king@canonical.com>
> >
> > Don't populate the read-only array 'prop' on the stack but
> > instead make it static. Makes the object code smaller by 20 bytes:
> >
> > Before:
> > text data bss dec hex filename
> > 71659 14614 576 86849 15341 trans.o
> >
> > After:
> > text data bss dec hex filename
> > 71479 14774 576 86829 1532d trans.o
> >
> > (gcc version 7.3.0 x86_64)
> >
> > Signed-off-by: Colin Ian King <colin.king@canonical.com>
> > ---
> > drivers/net/wireless/intel/iwlwifi/pcie/trans.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/wireless/intel/iwlwifi/pcie/trans.c b/drivers/net/wireless/intel/iwlwifi/pcie/trans.c
> > index 7229991ae70d..c4626ebe5da1 100644
> > --- a/drivers/net/wireless/intel/iwlwifi/pcie/trans.c
> > +++ b/drivers/net/wireless/intel/iwlwifi/pcie/trans.c
> > @@ -1946,7 +1946,7 @@ static void iwl_trans_pcie_removal_wk(struct work_struct *wk)
> > struct iwl_trans_pcie_removal *removal > > container_of(wk, struct iwl_trans_pcie_removal, work);
> > struct pci_dev *pdev = removal->pdev;
> > - char *prop[] = {"EVENT=INACCESSIBLE", NULL};
> > + static char *prop[] = {"EVENT=INACCESSIBLE", NULL};
> >
> > dev_err(&pdev->dev, "Device gone - attempting removal\n");
> > kobject_uevent_env(&pdev->dev.kobj, KOBJ_CHANGE, prop);
>
> Now what is happening is that prop is being reloaded
> each invocation with the constant addresses of the strings.
>
> It seems the prototype and function for kobject_uevent_env
> should change as well to avoid this.
>
> Perhaps this should become:
> ---
> drivers/net/wireless/intel/iwlwifi/pcie/trans.c | 2 +-
> include/linux/kobject.h | 2 +-
> lib/kobject_uevent.c | 2 +-
> 3 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/wireless/intel/iwlwifi/pcie/trans.c b/drivers/net/wireless/intel/iwlwifi/pcie/trans.c
> index 7229991ae70d..6668a8aad22e 100644
> --- a/drivers/net/wireless/intel/iwlwifi/pcie/trans.c
> +++ b/drivers/net/wireless/intel/iwlwifi/pcie/trans.c
> @@ -1946,7 +1946,7 @@ static void iwl_trans_pcie_removal_wk(struct work_struct *wk)
> struct iwl_trans_pcie_removal *removal > container_of(wk, struct iwl_trans_pcie_removal, work);
> struct pci_dev *pdev = removal->pdev;
> - char *prop[] = {"EVENT=INACCESSIBLE", NULL};
> + static const char * const prop[] = {"EVENT=INACCESSIBLE", NULL};
>
> dev_err(&pdev->dev, "Device gone - attempting removal\n");
> kobject_uevent_env(&pdev->dev.kobj, KOBJ_CHANGE, prop);
> diff --git a/include/linux/kobject.h b/include/linux/kobject.h
> index 7f6f93c3df9c..9f5cf553dd1e 100644
> --- a/include/linux/kobject.h
> +++ b/include/linux/kobject.h
> @@ -217,7 +217,7 @@ extern struct kobject *firmware_kobj;
>
> int kobject_uevent(struct kobject *kobj, enum kobject_action action);
> int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
> - char *envp[]);
> + const char * const envp[]);
> int kobject_synth_uevent(struct kobject *kobj, const char *buf, size_t count);
>
> __printf(2, 3)
> diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c
> index 63d0816ab23b..9107989a0cc8 100644
> --- a/lib/kobject_uevent.c
> +++ b/lib/kobject_uevent.c
> @@ -452,7 +452,7 @@ static void zap_modalias_env(struct kobj_uevent_env *env)
> * corresponding error when it fails.
> */
> int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
> - char *envp_ext[])
> + const char * const envp_ext[])
> {
> struct kobj_uevent_env *env;
> const char *action_string = kobject_actions[action];

No objection from me, care to make it a real patch so that I can apply
it after 4.18-rc1 is out?

thanks,

greg k-h