Date: Mon, 25 Oct 2010 11:42:42 +0200 From: Clemens Ladisch Subject: firewire: ohci: avoid reallocation of AR buffers Freeing an AR buffer page just to allocate a new page immediately afterwards is not only a pointless effort but also dangerous because the allocation can fail, which would result in an oops later. Split ar_context_add_page() into two functions so that we can reuse the old page directly. Signed-off-by: Clemens Ladisch Tested-by: Maxim Levitsky Signed-off-by: Stefan Richter --- drivers/firewire/ohci.c | 28 ++++++++++++++++------------ 1 file changed, 16 insertions(+), 12 deletions(-) Index: b/drivers/firewire/ohci.c =================================================================== --- a/drivers/firewire/ohci.c +++ b/drivers/firewire/ohci.c @@ -580,17 +580,11 @@ static int ohci_update_phy_reg(struct fw return ret; } -static int ar_context_add_page(struct ar_context *ctx) +static void ar_context_link_page(struct ar_context *ctx, + struct ar_buffer *ab, dma_addr_t ab_bus) { - struct device *dev = ctx->ohci->card.device; - struct ar_buffer *ab; - dma_addr_t uninitialized_var(ab_bus); size_t offset; - ab = dma_alloc_coherent(dev, PAGE_SIZE, &ab_bus, GFP_ATOMIC); - if (ab == NULL) - return -ENOMEM; - ab->next = NULL; memset(&ab->descriptor, 0, sizeof(ab->descriptor)); ab->descriptor.control = cpu_to_le16(DESCRIPTOR_INPUT_MORE | @@ -609,6 +603,19 @@ static int ar_context_add_page(struct ar reg_write(ctx->ohci, CONTROL_SET(ctx->regs), CONTEXT_WAKE); flush_writes(ctx->ohci); +} + +static int ar_context_add_page(struct ar_context *ctx) +{ + struct device *dev = ctx->ohci->card.device; + struct ar_buffer *ab; + dma_addr_t uninitialized_var(ab_bus); + + ab = dma_alloc_coherent(dev, PAGE_SIZE, &ab_bus, GFP_ATOMIC); + if (ab == NULL) + return -ENOMEM; + + ar_context_link_page(ctx, ab, ab_bus); return 0; } @@ -733,7 +740,6 @@ static __le32 *handle_ar_packet(struct a static void ar_context_tasklet(unsigned long data) { struct ar_context *ctx = (struct ar_context *)data; - struct fw_ohci *ohci = ctx->ohci; struct ar_buffer *ab; struct descriptor *d; void *buffer, *end; @@ -802,9 +808,7 @@ static void ar_context_tasklet(unsigned ctx->current_buffer = ab; ctx->pointer = end; - dma_free_coherent(ohci->card.device, PAGE_SIZE, - start, start_bus); - ar_context_add_page(ctx); + ar_context_link_page(ctx, start, start_bus); } else { ctx->pointer = start + PAGE_SIZE; }