From: "Rafael J. Wysocki" 1) use atomic_add_unless() instead of atomic_dec_and_test()/atomic_inc(), 2) remove a (unnecessary) memory barrier, 3) drop (unnecessary) access_ok() (actually the page will get released when the device is closed, so we don't need to worry if put_user() fails). Signed-off-by: Rafael J. Wysocki Acked-by: Pavel Machek Signed-off-by: Andrew Morton --- kernel/power/user.c | 11 ++--------- 1 files changed, 2 insertions(+), 9 deletions(-) diff -puN kernel/power/user.c~swsusp-userland-interface-update kernel/power/user.c --- 25/kernel/power/user.c~swsusp-userland-interface-update Fri Jan 27 13:41:21 2006 +++ 25-akpm/kernel/power/user.c Fri Jan 27 13:41:21 2006 @@ -40,10 +40,8 @@ static int snapshot_open(struct inode *i { struct snapshot_data *data; - if (!atomic_dec_and_test(&device_available)) { - atomic_inc(&device_available); + if (!atomic_add_unless(&device_available, -1, 0)) return -EBUSY; - } if ((filp->f_flags & O_ACCMODE) == O_RDWR) return -ENOSYS; @@ -198,7 +196,6 @@ static int snapshot_ioctl(struct inode * pm_prepare_console(); error = device_suspend(PMSG_FREEZE); if (!error) { - mb(); error = swsusp_resume(); device_resume(); } @@ -223,10 +220,6 @@ static int snapshot_ioctl(struct inode * break; case SNAPSHOT_GET_SWAP_PAGE: - if (!access_ok(VERIFY_WRITE, (unsigned long __user *)arg, _IOC_SIZE(cmd))) { - error = -EINVAL; - break; - } if (data->swap < 0 || data->swap >= MAX_SWAPFILES) { error = -ENODEV; break; @@ -241,7 +234,7 @@ static int snapshot_ioctl(struct inode * offset = alloc_swap_page(data->swap, data->bitmap); if (offset) { offset <<= PAGE_SHIFT; - __put_user(offset, (loff_t __user *)arg); + error = put_user(offset, (loff_t __user *)arg); } else { error = -ENOSPC; } _