From aae86e8adb3bbf5256eebe76500cf7254365753c Mon Sep 17 00:00:00 2001 From: Michal Nazarewicz Date: Mon, 15 Mar 2010 21:38:31 +0100 Subject: [PATCH] USB: f_mass_storage: dynamic buffers for better alignment "Static" buffers in fsg_buffhd structure (ie. fields which are arrays rather then pointers to dynamically allocated memory) are not aligned to any "big" power of two which may lead to poor DMA performance (copying "by hand" of head or tail) or no DMA at all even if otherwise hardware supports it. Therefore, this patch makes mass storage function use kmalloc()ed buffers which are (because of their size) page aligned (which should be enough for any hardware). Signed-off-by: Michal Nazarewicz Cc: Kyungmin Park Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/f_mass_storage.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-) diff --git a/drivers/usb/gadget/f_mass_storage.c b/drivers/usb/gadget/f_mass_storage.c index f4911c0..218f51d 100644 --- a/drivers/usb/gadget/f_mass_storage.c +++ b/drivers/usb/gadget/f_mass_storage.c @@ -302,7 +302,6 @@ static const char fsg_string_interface[] = "Mass Storage"; #define FSG_NO_INTR_EP 1 -#define FSG_BUFFHD_STATIC_BUFFER 1 #define FSG_NO_DEVICE_STRINGS 1 #define FSG_NO_OTG 1 #define FSG_NO_INTR_EP 1 @@ -2762,13 +2761,19 @@ static struct fsg_common *fsg_common_init(struct fsg_common *common, /* Data buffers cyclic list */ - /* Buffers in buffhds are static -- no need for additional - * allocation. */ bh = common->buffhds; - i = FSG_NUM_BUFFERS - 1; + i = FSG_NUM_BUFFERS; + goto buffhds_first_it; do { bh->next = bh + 1; - } while (++bh, --i); + ++bh; +buffhds_first_it: + bh->buf = kmalloc(FSG_BUFLEN, GFP_KERNEL); + if (unlikely(!bh->buf)) { + rc = -ENOMEM; + goto error_release; + } + } while (--i); bh->next = common->buffhds; @@ -2871,6 +2876,7 @@ static void fsg_common_release(struct kref *ref) container_of(ref, struct fsg_common, ref); unsigned i = common->nluns; struct fsg_lun *lun = common->luns; + struct fsg_buffhd *bh; /* If the thread isn't already dead, tell it to exit now */ if (common->state != FSG_STATE_TERMINATED) { @@ -2892,6 +2898,13 @@ static void fsg_common_release(struct kref *ref) } kfree(common->luns); + + i = FSG_NUM_BUFFERS; + bh = common->buffhds; + do { + kfree(bh->buf); + } while (++bh, --i); + if (common->free_storage_on_release) kfree(common); } -- 2.7.4