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Subject[PATCH 05/11] uml ubd driver: change ubd_lock to be a mutex
Date
From: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>

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>
---

arch/um/drivers/ubd_kern.c | 23 ++++++++++++-----------
1 files changed, 12 insertions(+), 11 deletions(-)

diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c
index 23663b7..e4fd29a 100644
--- 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
#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, i
}

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, i
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, i
}

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);
}

@@ -716,11 +717,11 @@ 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);
}
@@ -737,7 +738,7 @@ static int ubd_get_config(char *name, ch
}

ubd_dev = &ubd_devs[n];
- spin_lock(&ubd_lock);
+ mutex_lock(&ubd_lock);

if(ubd_dev->file == NULL){
CONFIG_CHUNK(str, size, len, "", 1);
@@ -753,7 +754,7 @@ static int ubd_get_config(char *name, ch
else CONFIG_CHUNK(str, size, len, "", 1);

out:
- spin_unlock(&ubd_lock);
+ mutex_unlock(&ubd_lock);
return(len);
}

@@ -772,7 +773,7 @@ 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;
@@ -801,7 +802,7 @@ 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;
}

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