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authorSebastian Andrzej Siewior <bigeasy@linutronix.de>2014-12-05 15:13:54 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-03-06 14:43:30 -0800
commitdf24955beb93b85b0f53ed249811411ae9f0890f (patch)
tree61bdc3fe64ec7d8b289cfe07e07c2ae61187104a
parent5b8e6d47e5af9081320ac50f354f6ff609e32105 (diff)
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usb: core: buffer: smallest buffer should start at ARCH_DMA_MINALIGN
commit 5efd2ea8c9f4f12916ffc8ba636792ce052f6911 upstream. the following error pops up during "testusb -a -t 10" | musb-hdrc musb-hdrc.1.auto: dma_pool_free buffer-128, f134e000/be842000 (bad dma) hcd_buffer_create() creates a few buffers, the smallest has 32 bytes of size. ARCH_KMALLOC_MINALIGN is set to 64 bytes. This combo results in hcd_buffer_alloc() returning memory which is 32 bytes aligned and it might by identified by buffer_offset() as another buffer. This means the buffer which is on a 32 byte boundary will not get freed, instead it tries to free another buffer with the error message. This patch fixes the issue by creating the smallest DMA buffer with the size of ARCH_KMALLOC_MINALIGN (or 32 in case ARCH_KMALLOC_MINALIGN is smaller). This might be 32, 64 or even 128 bytes. The next three pools will have the size 128, 512 and 2048. In case the smallest pool is 128 bytes then we have only three pools instead of four (and zero the first entry in the array). The last pool size is always 2048 bytes which is the assumed PAGE_SIZE / 2 of 4096. I doubt it makes sense to continue using PAGE_SIZE / 2 where we would end up with 8KiB buffer in case we have 16KiB pages. Instead I think it makes sense to have a common size(s) and extend them if there is need to. There is a BUILD_BUG_ON() now in case someone has a minalign of more than 128 bytes. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Acked-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/usb/core/buffer.c26
-rw-r--r--drivers/usb/core/usb.c1
-rw-r--r--include/linux/usb/hcd.h1
3 files changed, 19 insertions, 9 deletions
diff --git a/drivers/usb/core/buffer.c b/drivers/usb/core/buffer.c
index 684ef70dc09d..506b969ea7fd 100644
--- a/drivers/usb/core/buffer.c
+++ b/drivers/usb/core/buffer.c
@@ -22,17 +22,25 @@
*/
/* FIXME tune these based on pool statistics ... */
-static const size_t pool_max[HCD_BUFFER_POOLS] = {
- /* platforms without dma-friendly caches might need to
- * prevent cacheline sharing...
- */
- 32,
- 128,
- 512,
- PAGE_SIZE / 2
- /* bigger --> allocate pages */
+static size_t pool_max[HCD_BUFFER_POOLS] = {
+ 32, 128, 512, 2048,
};
+void __init usb_init_pool_max(void)
+{
+ /*
+ * The pool_max values must never be smaller than
+ * ARCH_KMALLOC_MINALIGN.
+ */
+ if (ARCH_KMALLOC_MINALIGN <= 32)
+ ; /* Original value is okay */
+ else if (ARCH_KMALLOC_MINALIGN <= 64)
+ pool_max[0] = 64;
+ else if (ARCH_KMALLOC_MINALIGN <= 128)
+ pool_max[0] = 0; /* Don't use this pool */
+ else
+ BUILD_BUG(); /* We don't allow this */
+}
/* SETUP primitives */
diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
index 4d1144990d4c..a92273026ecc 100644
--- a/drivers/usb/core/usb.c
+++ b/drivers/usb/core/usb.c
@@ -1050,6 +1050,7 @@ static int __init usb_init(void)
pr_info("%s: USB support disabled\n", usbcore_name);
return 0;
}
+ usb_init_pool_max();
retval = usb_debugfs_init();
if (retval)
diff --git a/include/linux/usb/hcd.h b/include/linux/usb/hcd.h
index efe8d8a7c7ad..e34bce3781ee 100644
--- a/include/linux/usb/hcd.h
+++ b/include/linux/usb/hcd.h
@@ -447,6 +447,7 @@ extern const struct dev_pm_ops usb_hcd_pci_pm_ops;
#endif /* CONFIG_PCI */
/* pci-ish (pdev null is ok) buffer alloc/mapping support */
+void usb_init_pool_max(void);
int hcd_buffer_create(struct usb_hcd *hcd);
void hcd_buffer_destroy(struct usb_hcd *hcd);