Attachment 316622 Details for Bug 185585 – re-implement (un)registering 32-bit compat ioctls using refcounts x86_64

[patch] re-implement (un)registering 32-bit compat ioctls using refcounts x86_64

compat.patch (text/plain), 5.19 KB, created by Jason Baron on 2008-09-12 20:13:54 UTC

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Creator: Jason Baron

Created: 2008-09-12 20:13:54 UTC

Size: 5.19 KB

patch

obsolete

>diff --git a/fs/compat.c b/fs/compat.c
>index ac51f8f..1ef0d43 100644
>--- a/fs/compat.c
>+++ b/fs/compat.c
>@@ -252,6 +252,16 @@ out:
> static struct ioctl_trans *ioctl32_hash_table[IOCTL_HASHSIZE];
> static DECLARE_RWSEM(ioctl32_sem);
> 
>+/* create a parallel hash table that uses refcounts to allow multiple
>+   parallel (un)register. Parallel table works around KABI issues */
>+
>+struct ioctl32_refcount {
>+	int count;
>+	wait_queue_head_t ref_wait;
>+	struct ioctl32_refcount *next;
>+};
>+static struct ioctl32_refcount *ioctl32_refcount_table[IOCTL_HASHSIZE];
>+
> extern struct ioctl_trans ioctl_start[];
> extern int ioctl_table_size;
> 
>@@ -260,26 +270,40 @@ static inline unsigned long ioctl32_hash(unsigned long cmd)
> 	return (((cmd >> 6) ^ (cmd >> 4) ^ cmd)) % IOCTL_HASHSIZE;
> }
> 
>-static void ioctl32_insert_translation(struct ioctl_trans *trans)
>+static int ioctl32_insert_translation(struct ioctl_trans *trans)
> {
> 	unsigned long hash;
> 	struct ioctl_trans *t;
>+	struct ioctl32_refcount *new_ref, *r;
>+
>+	new_ref = kmalloc(sizeof(*new_ref), GFP_KERNEL);
>+	if (!new_ref)
>+		return -ENOMEM;
>+	new_ref->count = 0;
>+	init_waitqueue_head(&new_ref->ref_wait);
>+	new_ref->next = NULL;
> 
> 	hash = ioctl32_hash (trans->cmd);
>-	if (!ioctl32_hash_table[hash])
>+	if (!ioctl32_hash_table[hash]) {
> 		ioctl32_hash_table[hash] = trans;
>-	else {
>+		ioctl32_refcount_table[hash] = new_ref;
>+	} else {
> 		t = ioctl32_hash_table[hash];
>+		r = ioctl32_refcount_table[hash];
> 		while (t->next)
> 			t = t->next;
>+		while (r->next)
>+			r = r->next;
> 		trans->next = NULL;
> 		t->next = trans;
>+		r->next = new_ref;
> 	}
>+	return 0;
> }
> 
> static int __init init_sys32_ioctl(void)
> {
>-	int i;
>+	int i, ret;
> 
> 	for (i = 0; i < ioctl_table_size; i++) {
> 		if (ioctl_start[i].next != 0) { 
>@@ -287,7 +311,9 @@ static int __init init_sys32_ioctl(void)
> 			return -1;
> 		}
> 
>-		ioctl32_insert_translation(&ioctl_start[i]);
>+		ret = ioctl32_insert_translation(&ioctl_start[i]);
>+		if (ret)
>+			return -1;
> 	}
> 	return 0;
> }
>@@ -300,6 +326,7 @@ int register_ioctl32_conversion(unsigned int cmd,
> 	struct ioctl_trans *t;
> 	struct ioctl_trans *new_t;
> 	unsigned long hash = ioctl32_hash(cmd);
>+	int ret = 0;
> 
> 	new_t = kmalloc(sizeof(*new_t), GFP_KERNEL);
> 	if (!new_t)
>@@ -318,10 +345,9 @@ int register_ioctl32_conversion(unsigned int cmd,
> 	new_t->next = NULL;
> 	new_t->cmd = cmd;
> 	new_t->handler = handler;
>-	ioctl32_insert_translation(new_t);
>-
>+	ret = ioctl32_insert_translation(new_t);
> 	up_write(&ioctl32_sem);
>-	return 0;
>+	return ret;
> }
> EXPORT_SYMBOL(register_ioctl32_conversion);
> 
>@@ -339,10 +365,14 @@ int unregister_ioctl32_conversion(unsigned int cmd)
> {
> 	unsigned long hash = ioctl32_hash(cmd);
> 	struct ioctl_trans *t, *t1;
>+	struct ioctl32_refcount *r, *r1;
> 
>+restart:
> 	down_write(&ioctl32_sem);
> 
> 	t = ioctl32_hash_table[hash];
>+	r = ioctl32_refcount_table[hash];
>+	
> 	if (!t) { 
> 		up_write(&ioctl32_sem);
> 		return -EINVAL;
>@@ -353,28 +383,46 @@ int unregister_ioctl32_conversion(unsigned int cmd)
> 			printk("%p tried to unregister builtin ioctl %x\n",
> 			       __builtin_return_address(0), cmd);
> 		} else { 
>+			if (r->count) {
>+				up_write(&ioctl32_sem);
>+				if(wait_event_interruptible(r->ref_wait, r->count == 0) < 0)
>+					return -ERESTARTSYS;
>+				goto restart;
>+			}	
> 			ioctl32_hash_table[hash] = t->next;
>+			ioctl32_refcount_table[hash] = r->next;
> 			up_write(&ioctl32_sem);
> 			kfree(t);
>+			kfree(r);
> 			return 0;
> 		}
> 	} 
> 	while (t->next) {
> 		t1 = t->next;
>+		r1 = r->next;
> 		if (t1->cmd == cmd) { 
> 			if (builtin_ioctl(t1)) {
> 				printk("%p tried to unregister builtin "
> 					"ioctl %x\n",
> 					__builtin_return_address(0), cmd);
> 				goto out;
>-			} else { 
>+			} else {
>+				if (r1->count) {
>+					up_write(&ioctl32_sem);
>+					if(wait_event_interruptible(r->ref_wait, r->count == 0) < 0)
>+						return -ERESTARTSYS;
>+					goto restart;
>+				}
> 				t->next = t1->next;
>+				r->next = r1->next;
> 				up_write(&ioctl32_sem);
> 				kfree(t1);
>+				kfree(r1);
> 				return 0;
> 			}
> 		}
> 		t = t1;
>+		r = r1;
> 	}
> 	printk(KERN_ERR "Trying to free unknown 32bit ioctl handler %x\n",
> 				cmd);
>@@ -390,6 +438,7 @@ asmlinkage long compat_sys_ioctl(unsigned int fd, unsigned int cmd,
> 	struct file * filp;
> 	int error = -EBADF;
> 	struct ioctl_trans *t;
>+	struct ioctl32_refcount *r;
> 
> 	filp = fget(fd);
> 	if(!filp)
>@@ -400,24 +449,33 @@ asmlinkage long compat_sys_ioctl(unsigned int fd, unsigned int cmd,
> 		goto out;
> 	}
> 
>-	down_read(&ioctl32_sem);
>+	down_write(&ioctl32_sem);
> 
> 	t = ioctl32_hash_table[ioctl32_hash (cmd)];
>+	r = ioctl32_refcount_table[ioctl32_hash(cmd)];
> 
>-	while (t && t->cmd != cmd)
>+	while (t && t->cmd != cmd) {
> 		t = t->next;
>+		r = r->next;
>+	}
> 	if (t) {
> 		if (t->handler) { 
>+			r->count += 1;
>+			up_write(&ioctl32_sem);
> 			lock_kernel();
> 			error = t->handler(fd, cmd, arg, filp);
> 			unlock_kernel();
>-			up_read(&ioctl32_sem);
>+			down_write(&ioctl32_sem);
>+			r->count -= 1;
>+			if (r->count == 0)
>+				wake_up_all(&r->ref_wait);
>+			up_write(&ioctl32_sem);
> 		} else {
>-			up_read(&ioctl32_sem);
>+			up_write(&ioctl32_sem);
> 			error = sys_ioctl(fd, cmd, arg);
> 		}
> 	} else {
>-		up_read(&ioctl32_sem);
>+		up_write(&ioctl32_sem);
> 		if (cmd >= SIOCDEVPRIVATE && cmd <= (SIOCDEVPRIVATE + 15)) {
> 			error = siocdevprivate_ioctl(fd, cmd, arg);
> 		} else {

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Attachments on bug 185585: 316622