On Fri 20 Mar 09:02 PDT 2020, Alex Elder wrote: > Don't assume the receive buffer size is a power-of-2 number of pages. > Instead, define the receive buffer size independently, and then > compute the page order from that size when needed. > > This fixes a build problem that arises when the ARM64_PAGE_SHIFT > config option is set to have a page size greater than 4KB. The > problem was identified by Linux Kernel Functional Testing. > > The IPA code basically assumed the page size to be 4KB. A larger page > size caused the receive buffer size to become correspondingly larger > (32KB or 128KB for ARM64_16K_PAGES and ARM64_64K_PAGES, respectively). > The receive buffer size is used to compute an "aggregation byte limit" > value that gets programmed into the hardware, and the large page sizes > caused that limit value to be too big to fit in a 5 bit field. This > triggered a BUILD_BUG_ON() call in ipa_endpoint_validate_build(). > > This fix causes a lot of receive buffer memory to be wasted if > system is configured for page size greater than 4KB. But such a > misguided configuration will now build successfully. > > Reported-by: Naresh Kamboju <naresh.kamboju@xxxxxxxxxx> > Signed-off-by: Alex Elder <elder@xxxxxxxxxx> Seems better than relying on PAGE_SIZE. Reviewed-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx> Regards, Bjorn > --- > > Dave, I *hope* this is it for IPA for this release. -Alex > > drivers/net/ipa/ipa_endpoint.c | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > > diff --git a/drivers/net/ipa/ipa_endpoint.c b/drivers/net/ipa/ipa_endpoint.c > index 217cbf337ad7..6de03be28784 100644 > --- a/drivers/net/ipa/ipa_endpoint.c > +++ b/drivers/net/ipa/ipa_endpoint.c > @@ -26,8 +26,8 @@ > > #define IPA_REPLENISH_BATCH 16 > > -#define IPA_RX_BUFFER_SIZE (PAGE_SIZE << IPA_RX_BUFFER_ORDER) > -#define IPA_RX_BUFFER_ORDER 1 /* 8KB endpoint RX buffers (2 pages) */ > +/* RX buffer is 1 page (or a power-of-2 contiguous pages) */ > +#define IPA_RX_BUFFER_SIZE 8192 /* PAGE_SIZE > 4096 wastes a LOT */ > > /* The amount of RX buffer space consumed by standard skb overhead */ > #define IPA_RX_BUFFER_OVERHEAD (PAGE_SIZE - SKB_MAX_ORDER(NET_SKB_PAD, 0)) > @@ -758,7 +758,7 @@ static int ipa_endpoint_replenish_one(struct ipa_endpoint *endpoint) > u32 len; > int ret; > > - page = dev_alloc_pages(IPA_RX_BUFFER_ORDER); > + page = dev_alloc_pages(get_order(IPA_RX_BUFFER_SIZE)); > if (!page) > return -ENOMEM; > > @@ -787,7 +787,7 @@ static int ipa_endpoint_replenish_one(struct ipa_endpoint *endpoint) > err_trans_free: > gsi_trans_free(trans); > err_free_pages: > - __free_pages(page, IPA_RX_BUFFER_ORDER); > + __free_pages(page, get_order(IPA_RX_BUFFER_SIZE)); > > return -ENOMEM; > } > @@ -1073,7 +1073,7 @@ void ipa_endpoint_trans_release(struct ipa_endpoint *endpoint, > struct page *page = trans->data; > > if (page) > - __free_pages(page, IPA_RX_BUFFER_ORDER); > + __free_pages(page, get_order(IPA_RX_BUFFER_SIZE)); > } > } > > -- > 2.20.1 >
