4.4-stable review patch. If anyone has any objections, please let me know.
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From: Mateusz Berezecki mateuszb@fastmail.fm
commit 1129d270cbfbb7e2b1ec3dede4a13930bdd10e41 upstream.
Promote a variable keeping track of USB transfer memory usage to a wider data type and allow for higher bandwidth transfers from a large number of USB devices connected to a single host.
Signed-off-by: Mateusz Berezecki mateuszb@fastmail.fm Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/usb/core/devio.c | 43 ++++++++++++++++--------------------------- 1 file changed, 16 insertions(+), 27 deletions(-)
--- a/drivers/usb/core/devio.c +++ b/drivers/usb/core/devio.c @@ -113,42 +113,35 @@ enum snoop_when { #define USB_DEVICE_DEV MKDEV(USB_DEVICE_MAJOR, 0)
/* Limit on the total amount of memory we can allocate for transfers */ -static unsigned usbfs_memory_mb = 16; +static u32 usbfs_memory_mb = 16; module_param(usbfs_memory_mb, uint, 0644); MODULE_PARM_DESC(usbfs_memory_mb, "maximum MB allowed for usbfs buffers (0 = no limit)");
-/* Hard limit, necessary to avoid arithmetic overflow */ -#define USBFS_XFER_MAX (UINT_MAX / 2 - 1000000) - -static atomic_t usbfs_memory_usage; /* Total memory currently allocated */ +static atomic64_t usbfs_memory_usage; /* Total memory currently allocated */
/* Check whether it's okay to allocate more memory for a transfer */ -static int usbfs_increase_memory_usage(unsigned amount) +static int usbfs_increase_memory_usage(u64 amount) { - unsigned lim; + u64 lim;
- /* - * Convert usbfs_memory_mb to bytes, avoiding overflows. - * 0 means use the hard limit (effectively unlimited). - */ lim = ACCESS_ONCE(usbfs_memory_mb); - if (lim == 0 || lim > (USBFS_XFER_MAX >> 20)) - lim = USBFS_XFER_MAX; - else - lim <<= 20; + lim <<= 20;
- atomic_add(amount, &usbfs_memory_usage); - if (atomic_read(&usbfs_memory_usage) <= lim) - return 0; - atomic_sub(amount, &usbfs_memory_usage); - return -ENOMEM; + atomic64_add(amount, &usbfs_memory_usage); + + if (lim > 0 && atomic64_read(&usbfs_memory_usage) > lim) { + atomic64_sub(amount, &usbfs_memory_usage); + return -ENOMEM; + } + + return 0; }
/* Memory for a transfer is being deallocated */ -static void usbfs_decrease_memory_usage(unsigned amount) +static void usbfs_decrease_memory_usage(u64 amount) { - atomic_sub(amount, &usbfs_memory_usage); + atomic64_sub(amount, &usbfs_memory_usage); }
static int connected(struct usb_dev_state *ps) @@ -1077,7 +1070,7 @@ static int proc_bulk(struct usb_dev_stat if (!usb_maxpacket(dev, pipe, !(bulk.ep & USB_DIR_IN))) return -EINVAL; len1 = bulk.len; - if (len1 >= USBFS_XFER_MAX) + if (len1 >= (INT_MAX - sizeof(struct urb))) return -EINVAL; ret = usbfs_increase_memory_usage(len1 + sizeof(struct urb)); if (ret) @@ -1424,10 +1417,6 @@ static int proc_do_submiturb(struct usb_ return -EINVAL; }
- if (uurb->buffer_length >= USBFS_XFER_MAX) { - ret = -EINVAL; - goto error; - } if (uurb->buffer_length > 0 && !access_ok(is_in ? VERIFY_WRITE : VERIFY_READ, uurb->buffer, uurb->buffer_length)) {