[PATCH] uml ubd driver: change ubd_lock to be a mutex

This lock protects ubd setup and teardown, so is only used in process context;
beyond that, during such setup memory allocations must be performed and some
generic functions which can sleep must be called (such as add_disk()).  So the
only correct solution is to make it a mutex instead of a spin_lock.  No other
change is done - this lock must be acquired in different places but it's done
afterwards.

Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c
index cdd82e8..a3061ae 100644 (file)
--- a/arch/um/drivers/ubd_kern.c
+++ b/arch/um/drivers/ubd_kern.c
@@ -107,7 +107,8 @@ static inline void ubd_set_bit(__u64 bit, unsigned char *data)
 #define DRIVER_NAME "uml-blkdev"
 
 static DEFINE_SPINLOCK(ubd_io_lock);
-static DEFINE_SPINLOCK(ubd_lock);
+
+static DEFINE_MUTEX(ubd_lock);
 
 static void (*do_ubd)(void);
 
@@ -314,7 +315,7 @@ static int ubd_setup_common(char *str, int *index_out)
                }
 
                err = 1;
-               spin_lock(&ubd_lock);
+               mutex_lock(&ubd_lock);
                if(fake_major != MAJOR_NR){
                        printk(KERN_ERR "Can't assign a fake major twice\n");
                        goto out1;
@@ -326,7 +327,7 @@ static int ubd_setup_common(char *str, int *index_out)
                       major);
                err = 0;
        out1:
-               spin_unlock(&ubd_lock);
+               mutex_unlock(&ubd_lock);
                return(err);
        }
 
@@ -343,7 +344,7 @@ static int ubd_setup_common(char *str, int *index_out)
        }
 
        err = 1;
-       spin_lock(&ubd_lock);
+       mutex_lock(&ubd_lock);
 
        ubd_dev = &ubd_devs[n];
        if(ubd_dev->file != NULL){
@@ -405,7 +406,7 @@ break_loop:
        ubd_dev->cow.file = backing_file;
        ubd_dev->boot_openflags = flags;
 out:
-       spin_unlock(&ubd_lock);
+       mutex_unlock(&ubd_lock);
        return(err);
 }
 
@@ -710,11 +711,11 @@ static int ubd_config(char *str)
        }
        if(n == -1) return(0);
 
-       spin_lock(&ubd_lock);
+       mutex_lock(&ubd_lock);
        err = ubd_add(n);
        if(err)
                ubd_devs[n].file = NULL;
-       spin_unlock(&ubd_lock);
+       mutex_unlock(&ubd_lock);
 
        return(err);
 }
@@ -731,7 +732,7 @@ static int ubd_get_config(char *name, char *str, int size, char **error_out)
        }
 
        ubd_dev = &ubd_devs[n];
-       spin_lock(&ubd_lock);
+       mutex_lock(&ubd_lock);
 
        if(ubd_dev->file == NULL){
                CONFIG_CHUNK(str, size, len, "", 1);
@@ -747,7 +748,7 @@ static int ubd_get_config(char *name, char *str, int size, char **error_out)
        else CONFIG_CHUNK(str, size, len, "", 1);
 
  out:
-       spin_unlock(&ubd_lock);
+       mutex_unlock(&ubd_lock);
        return(len);
 }
 
@@ -766,7 +767,7 @@ static int ubd_remove(int n)
        struct ubd *ubd_dev;
        int err = -ENODEV;
 
-       spin_lock(&ubd_lock);
+       mutex_lock(&ubd_lock);
 
        if(ubd_gendisk[n] == NULL)
                goto out;
@@ -795,7 +796,7 @@ static int ubd_remove(int n)
        *ubd_dev = ((struct ubd) DEFAULT_UBD);
        err = 0;
 out:
-       spin_unlock(&ubd_lock);
+       mutex_unlock(&ubd_lock);
        return err;
 }