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 <clemens@ladisch.de>
Tested-by: Maxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c
index 7570b71..b5ba666 100644
--- a/drivers/firewire/ohci.c
+++ b/drivers/firewire/ohci.c
@@ -577,17 +577,11 @@
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 |
@@ -606,6 +600,19 @@
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;
}
@@ -730,7 +737,6 @@
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;
@@ -799,9 +805,7 @@
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;
}