diff options
| author | Alan Stern <stern@rowland.harvard.edu> | 2011-11-17 16:41:35 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-11-18 11:09:07 -0800 |
| commit | 3f5eb8d5688a5266ab943cf94aebe4c0eea726a3 (patch) | |
| tree | f91c3a0743c1c7058704b20517f4c533c4a6dbb8 /drivers | |
| parent | add1aaeabe6b08ed26381a2a06e505b2f09c3ba5 (diff) | |
| download | linux-3f5eb8d5688a5266ab943cf94aebe4c0eea726a3.tar.gz | |
USB: make the usbfs memory limit configurable
The 16-MB global limit on memory used by usbfs isn't suitable for all
people. It's a reasonable default, but there are applications
(especially for SuperSpeed devices) that need a lot more.
This patch (as1498) creates a writable module parameter for usbcore to
control the global limit. The default is still 16 MB, but users can
change it at runtime, even after usbcore has been loaded. As a
special case, setting the value to 0 is treated the same as the hard
limit of 2047 MB.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/usb/core/devio.c | 26 |
1 files changed, 22 insertions, 4 deletions
diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c index b69768b7d226..d8cf06f186f2 100644 --- a/drivers/usb/core/devio.c +++ b/drivers/usb/core/devio.c @@ -110,15 +110,33 @@ enum snoop_when { #define USB_DEVICE_DEV MKDEV(USB_DEVICE_MAJOR, 0) /* Limit on the total amount of memory we can allocate for transfers */ -#define MAX_USBFS_MEMORY_USAGE 16777216 /* 16 MB */ +static unsigned 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 aithmetic overflow */ +#define USBFS_XFER_MAX (UINT_MAX / 2 - 1000000) static atomic_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) { + unsigned 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; + atomic_add(amount, &usbfs_memory_usage); - if (atomic_read(&usbfs_memory_usage) <= MAX_USBFS_MEMORY_USAGE) + if (atomic_read(&usbfs_memory_usage) <= lim) return 0; atomic_sub(amount, &usbfs_memory_usage); return -ENOMEM; @@ -907,7 +925,7 @@ static int proc_bulk(struct dev_state *ps, void __user *arg) if (!usb_maxpacket(dev, pipe, !(bulk.ep & USB_DIR_IN))) return -EINVAL; len1 = bulk.len; - if (len1 > MAX_USBFS_MEMORY_USAGE) + if (len1 >= USBFS_XFER_MAX) return -EINVAL; ret = usbfs_increase_memory_usage(len1 + sizeof(struct urb)); if (ret) @@ -1227,7 +1245,7 @@ static int proc_do_submiturb(struct dev_state *ps, struct usbdevfs_urb *uurb, return -EINVAL; } - if (uurb->buffer_length > MAX_USBFS_MEMORY_USAGE) { + if (uurb->buffer_length >= USBFS_XFER_MAX) { ret = -EINVAL; goto error; } |