diff options
| -rw-r--r-- | fs/compat_ioctl.c | 90 |
1 files changed, 44 insertions, 46 deletions
diff --git a/fs/compat_ioctl.c b/fs/compat_ioctl.c index 7895bdb0c304..b4873ae84ca1 100644 --- a/fs/compat_ioctl.c +++ b/fs/compat_ioctl.c @@ -111,6 +111,8 @@ #include <linux/dvb/frontend.h> #include <linux/dvb/video.h> +#include <linux/sort.h> + #ifdef CONFIG_SPARC #include <asm/fbio.h> #endif @@ -1048,15 +1050,13 @@ static int compat_ioctl_preallocate(struct file *file, unsigned long arg) } #endif +/* + * simple reversible transform to make our table more evenly + * distributed after sorting. + */ +#define XFORM(i) (((i) ^ ((i) << 27) ^ ((i) << 17)) & 0xffffffff) -struct ioctl_trans { - unsigned long cmd; - struct ioctl_trans *next; -}; - -/* pointer to compatible structure or no argument */ -#define COMPATIBLE_IOCTL(cmd) { (cmd), }, - +#define COMPATIBLE_IOCTL(cmd) XFORM(cmd), /* ioctl should not be warned about even if it's not implemented. Valid reasons to use this: - It is implemented with ->compat_ioctl on some device, but programs @@ -1066,7 +1066,7 @@ struct ioctl_trans { Most other reasons are not valid. */ #define IGNORE_IOCTL(cmd) COMPATIBLE_IOCTL(cmd) -static struct ioctl_trans ioctl_start[] = { +static unsigned int ioctl_pointer[] = { /* compatible ioctls first */ COMPATIBLE_IOCTL(0x4B50) /* KDGHWCLK - not in the kernel, but don't complain */ COMPATIBLE_IOCTL(0x4B51) /* KDSHWCLK - not in the kernel, but don't complain */ @@ -1710,14 +1710,6 @@ IGNORE_IOCTL(FBIOGCURSOR32) #endif }; -#define IOCTL_HASHSIZE 256 -static struct ioctl_trans *ioctl32_hash_table[IOCTL_HASHSIZE]; - -static inline unsigned long ioctl32_hash(unsigned long cmd) -{ - return (((cmd >> 6) ^ (cmd >> 4) ^ cmd)) % IOCTL_HASHSIZE; -} - /* * Convert common ioctl arguments based on their command number * @@ -1861,12 +1853,33 @@ static void compat_ioctl_error(struct file *filp, unsigned int fd, free_page((unsigned long)path); } +static int compat_ioctl_check_table(unsigned int xcmd) +{ + int i; + const int max = ARRAY_SIZE(ioctl_pointer) - 1; + + BUILD_BUG_ON(max >= (1 << 16)); + + /* guess initial offset into table, assuming a + normalized distribution */ + i = ((xcmd >> 16) * max) >> 16; + + /* do linear search up first, until greater or equal */ + while (ioctl_pointer[i] < xcmd && i < max) + i++; + + /* then do linear search down */ + while (ioctl_pointer[i] > xcmd && i > 0) + i--; + + return ioctl_pointer[i] == xcmd; +} + asmlinkage long compat_sys_ioctl(unsigned int fd, unsigned int cmd, unsigned long arg) { struct file *filp; int error = -EBADF; - struct ioctl_trans *t; int fput_needed; filp = fget_light(fd, &fput_needed); @@ -1923,10 +1936,8 @@ asmlinkage long compat_sys_ioctl(unsigned int fd, unsigned int cmd, break; } - for (t = ioctl32_hash_table[ioctl32_hash(cmd)]; t; t = t->next) { - if (t->cmd == cmd) - goto found_handler; - } + if (compat_ioctl_check_table(XFORM(cmd))) + goto found_handler; error = do_ioctl_trans(fd, cmd, arg, filp); if (error == -ENOIOCTLCMD) { @@ -1949,35 +1960,22 @@ asmlinkage long compat_sys_ioctl(unsigned int fd, unsigned int cmd, return error; } -static void ioctl32_insert_translation(struct ioctl_trans *trans) +static int __init init_sys32_ioctl_cmp(const void *p, const void *q) { - unsigned long hash; - struct ioctl_trans *t; - - hash = ioctl32_hash (trans->cmd); - if (!ioctl32_hash_table[hash]) - ioctl32_hash_table[hash] = trans; - else { - t = ioctl32_hash_table[hash]; - while (t->next) - t = t->next; - trans->next = NULL; - t->next = trans; - } + unsigned int a, b; + a = *(unsigned int *)p; + b = *(unsigned int *)q; + if (a > b) + return 1; + if (a < b) + return -1; + return 0; } static int __init init_sys32_ioctl(void) { - int i; - - for (i = 0; i < ARRAY_SIZE(ioctl_start); i++) { - if (ioctl_start[i].next) { - printk("ioctl translation %d bad\n",i); - return -1; - } - - ioctl32_insert_translation(&ioctl_start[i]); - } + sort(ioctl_pointer, ARRAY_SIZE(ioctl_pointer), sizeof(*ioctl_pointer), + init_sys32_ioctl_cmp, NULL); return 0; } __initcall(init_sys32_ioctl); |