On Fri, 9 Dec 2016, Mateusz Berezecki wrote: > This patch promotes a variable keeping track of USB transfer memory > usage to a wider data type, allowing higher bandwidth transfers from a > large number of USB devices connected to a single host. > > Signed-off-by: Mateusz Berezecki <mateu...@fastmail.fm> > --- > drivers/usb/core/devio.c | 24 ++++++++++++------------ > 1 file changed, 12 insertions(+), 12 deletions(-) > > diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c > index 4016dae..ca4c8581 100644 > --- a/drivers/usb/core/devio.c > +++ b/drivers/usb/core/devio.c > @@ -134,20 +134,20 @@ 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; > -module_param(usbfs_memory_mb, uint, 0644); > +static u64 usbfs_memory_mb = 16; > +module_param(usbfs_memory_mb, ullong, 0644); > MODULE_PARM_DESC(usbfs_memory_mb, > "maximum MB allowed for usbfs buffers (0 = no limit)");
This parameter can remain a 32-bit quantity, since it gives the memory limit in MB. > -/* Hard limit, necessary to avoid arithmetic overflow */ > -#define USBFS_XFER_MAX (UINT_MAX / 2 - 1000000) > +/* Hard limit */ > +#define USBFS_XFER_MAX (1ull << 32) Only 4 GB? Why not allow a lot higher? This only doubles the existing hard limit, roughly. In theory this could be as large as (1ull << 52) -- that's about 4 billion MB, or if you prefer, 4 million GB. The rest of the patch looks okay. Alan Stern > -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. > @@ -159,17 +159,17 @@ static int usbfs_increase_memory_usage(unsigned amount) > else > lim <<= 20; > > - atomic_add(amount, &usbfs_memory_usage); > - if (atomic_read(&usbfs_memory_usage) <= lim) > + atomic64_add(amount, &usbfs_memory_usage); > + if (atomic64_read(&usbfs_memory_usage) <= lim) > return 0; > - atomic_sub(amount, &usbfs_memory_usage); > + atomic64_sub(amount, &usbfs_memory_usage); > return -ENOMEM; > } > > /* 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) -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html