On Tue, 25 Nov 2014, Sebastian Andrzej Siewior wrote:
> On 11/24/2014 11:00 PM, Alan Stern wrote:
> >> diff --git a/drivers/usb/core/buffer.c b/drivers/usb/core/buffer.c
> >> index 684ef70dc09d..a80d1ec8b1b0 100644
> >> --- a/drivers/usb/core/buffer.c
> >> +++ b/drivers/usb/core/buffer.c
> >> @@ -26,7 +26,11 @@ static const size_t pool_max[HCD_BUFFER_POOLS] = {
> >> /* platforms without dma-friendly caches might need to
> >> * prevent cacheline sharing...
> >> */
> >> +#if ARCH_KMALLOC_MINALIGN <= 32
> >> 32,
> >> +#elif ARCH_KMALLOC_MINALIGN <= 64
> >> + 64,
> >> +#endif
> >> 128,
> >> 512,
> >> PAGE_SIZE / 2
> >> @@ -58,6 +62,7 @@ int hcd_buffer_create(struct usb_hcd *hcd)
> >> !(hcd->driver->flags & HCD_LOCAL_MEM))
> >> return 0;
> >>
> >> + BUILD_BUG_ON(ARCH_KMALLOC_MINALIGN > 128);
> >> for (i = 0; i < HCD_BUFFER_POOLS; i++) {
> >> size = pool_max[i];
> >> if (!size)
> >> diff --git a/include/linux/usb/hcd.h b/include/linux/usb/hcd.h
> >> index cd96a2bc3388..1e2234ca448d 100644
> >> --- a/include/linux/usb/hcd.h
> >> +++ b/include/linux/usb/hcd.h
> >> @@ -23,6 +23,7 @@
> >>
> >> #include <linux/rwsem.h>
> >> #include <linux/interrupt.h>
> >> +#include <linux/slab.h>
> >>
> >> #define MAX_TOPO_LEVEL 6
> >>
> >> @@ -171,8 +172,11 @@ struct usb_hcd {
> >> struct usb_hcd *shared_hcd;
> >> struct usb_hcd *primary_hcd;
> >>
> >> -
> >> -#define HCD_BUFFER_POOLS 4
> >> +#if ARCH_KMALLOC_MINALIGN <= 64
> >> + #define HCD_BUFFER_POOLS 4
> >> +#else
> >> + #define HCD_BUFFER_POOLS 3
> >> +#endif
> >> struct dma_pool *pool[HCD_BUFFER_POOLS];
> >
> > What about the ARCH_KMALLOC_MINALIGN <= 32 case?
>
> since <= 32 is also <= 64 there will be 4 pools. The first pool will
> have 32 bytes in size, there will be no 64byte pool (it will behave
> like it does now).
> But this does not really answer your question, does it? I assume I
> overlook the obvious thing.
Ah, okay, now I see. The code is a slightly confusing, but correct.
How about refactoring it a little to make it clearer? Like this:
static const size_t pool_max[HCD_BUFFER_POOLS] = {
#if ARCH_KMALLOC_MINALIGN <= 32
32, 128, 512, PAGE_SIZE / 2
#elif ARCH_KMALLOC_MINALIGN <= 64
64, 128, 512, PAGE_SIZE / 2
#else
128, 512, PAGE_SIZE / 2
#endif
};
/* If ARCH_KMALLOC_MINALIGN > 128 we will cause a BUILD_BUG */
Alan Stern
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