Message ID | 5655DFFC.2050107@free.fr |
---|---|
State | Not Applicable, archived |
Delegated to: | David Miller |
Headers | show |
Mason <slash.tmp@free.fr> writes: > On 25/11/2015 17:16, Måns Rullgård wrote: > >> Alexander Duyck writes: >> >>> On Wed, Nov 25, 2015 at 5:04 AM, Måns Rullgård wrote: >>> >>>> Mason writes: >>>> >>>>> On 25/11/2015 13:45, Måns Rullgård wrote: >>>>> >>>>>> Mason wrote: >>>>>> >>>>>>> On 19/11/2015 14:02, Mans Rullgard wrote: >>>>>>> >>>>>>>> + if (dma_mapping_error(&dev->dev, dma_addr)) { >>>>>>>> + skb_free_frag(data); >>>>>>>> + return -ENOMEM; >>>>>>>> + } >>>>>>> >>>>>>> I'm back-porting this driver to 4.1 >>>>>>> >>>>>>> skb_free_frag() was introduced in 4.2 by 181edb2bfa22b IIUC. >>>>>>> >>>>>>> +static inline void skb_free_frag(void *addr) >>>>>>> +{ >>>>>>> + __free_page_frag(addr); >>>>>>> +} >>>>>>> >>>>>>> Should I just copy the definition of __free_page_frag() ? >>>>>> >>>>>> Looks like it ought to work. Try and find out. Not that you'll ever >>>>>> hit that error condition unless you fake it. >>>>> >>>>> Turns out __free_pages_ok() is static and I'd rather not touch >>>>> mm/page_alloc.c in my back-port. >>>>> >>>>> Since you say the error condition is rare, I think I'll go with >>>>> the code that 181edb2bfa22b replaced (put_page, IIUC). >>>>> >>>>> #include <linux/version.h> >>>>> #if LINUX_VERSION_CODE < KERNEL_VERSION(4,2,0) >>>>> #define skb_free_frag(data) put_page(virt_to_head_page(data)) >>>>> #else >>>>> #error DELETE ME NOW (see commit 181edb2bfa22b) >>>>> #endif >>>> >>>> You can simply put_page(page) instead since we already have the >>>> virt_to_head_page() a few lines up. >>> >>> What you could do is use __free_pages instead of __free_pages_ok. >>> Generally you will want to use __free_pages instead of put_page just >>> to avoid a bunch of unnecessary tests and function pointer accesses. >> >> Note that this is on a should-never-happen error path, so there's no >> need to be counting cycles. > > Per Mans' advice, I have locally committed this patch: > > diff --git a/drivers/net/ethernet/aurora/nb8800.c b/drivers/net/ethernet/aurora/nb8800.c > index ecc4a334c507..9f929be96b74 100644 > --- a/drivers/net/ethernet/aurora/nb8800.c > +++ b/drivers/net/ethernet/aurora/nb8800.c > @@ -39,6 +39,13 @@ > > #include "nb8800.h" > > +#include <linux/version.h> > +#if LINUX_VERSION_CODE < KERNEL_VERSION(4,2,0) > +#define skb_free_frag(data) put_page(page) > +#else > +#error DELETE ME NOW (see commit 181edb2bfa22) > +#endif > + > static void nb8800_tx_done(struct net_device *dev); > static int nb8800_dma_stop(struct net_device *dev); That works only by accident due to how local variables are named. If you want a macro to emulate the new function, your first suggestion is better. I thought you were going to change the actual function.
diff --git a/drivers/net/ethernet/aurora/nb8800.c b/drivers/net/ethernet/aurora/nb8800.c index ecc4a334c507..9f929be96b74 100644 --- a/drivers/net/ethernet/aurora/nb8800.c +++ b/drivers/net/ethernet/aurora/nb8800.c @@ -39,6 +39,13 @@ #include "nb8800.h" +#include <linux/version.h> +#if LINUX_VERSION_CODE < KERNEL_VERSION(4,2,0) +#define skb_free_frag(data) put_page(page) +#else +#error DELETE ME NOW (see commit 181edb2bfa22) +#endif + static void nb8800_tx_done(struct net_device *dev); static int nb8800_dma_stop(struct net_device *dev);