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-rw-r--r--fs/compat_ioctl.c90
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);