2007-09-22 08:41:26

by Matti Linnanvuori

Subject: [PATCH] include/linux/mutex.h: unclear reference to convention

From: Matti Linnanvuori <[email protected]>

Reference to two different conventions is unnecessarily unclear unless you know them already and requires seeking and reading another file for understanding.

Signed-off-by: Matti Linnanvuori <[email protected]>
---

--- linux-2.6.23-rc7/include/linux/mutex.h 2007-09-22 11:09:42.223763000 +0300
+++ linux-2.6.23/include/linux/mutex.h 2007-09-22 11:11:19.416761000 +0300
@@ -132,9 +132,19 @@ extern int __must_check mutex_lock_inter
# define mutex_lock_interruptible_nested(lock, subclass) mutex_lock_interruptible(lock)
#endif

-/*
- * NOTE: mutex_trylock() follows the spin_trylock() convention,
- * not the down_trylock() convention!
+/***
+ * mutex_trylock - try acquire the mutex, without waiting
+ * @lock: the mutex to be acquired
+ *
+ * Try to acquire the mutex atomically. Returns 1 if the mutex
+ * has been acquired successfully, and 0 on contention.
+ *
+ * NOTE: this function follows the spin_trylock() convention, so
+ * it is negated to the down_trylock() return values! Be careful
+ * about this when converting semaphore users to mutexes.
+ *
+ * This function must not be used in interrupt context. The
+ * mutex must be released by the same task that acquired it.
*/
extern int fastcall mutex_trylock(struct mutex *lock);
extern void fastcall mutex_unlock(struct mutex *lock);





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2007-09-22 17:36:09

by Randy Dunlap

Subject: Re: [PATCH] include/linux/mutex.h: unclear reference to convention

On Sat, 22 Sep 2007 01:41:17 -0700 (PDT) Matti Linnanvuori wrote:

> From: Matti Linnanvuori <[email protected]>
>
> Reference to two different conventions is unnecessarily unclear unless you know them already and requires seeking and reading another file for understanding.


Could you hit the Return/Enter key about every 70-72 characters or so,
to break up those long lines?
Thanks.

> Signed-off-by: Matti Linnanvuori <[email protected]>
> ---
>
> --- linux-2.6.23-rc7/include/linux/mutex.h 2007-09-22 11:09:42.223763000 +0300
> +++ linux-2.6.23/include/linux/mutex.h 2007-09-22 11:11:19.416761000 +0300
> @@ -132,9 +132,19 @@ extern int __must_check mutex_lock_inter
> # define mutex_lock_interruptible_nested(lock, subclass) mutex_lock_interruptible(lock)
> #endif
>
> -/*
> - * NOTE: mutex_trylock() follows the spin_trylock() convention,
> - * not the down_trylock() convention!

Someone was trying to be helpful in include/linux/mutex.h.
The real doc for the function is in kernel/mutex.c (and pasted
below).

Another convention is that we put kernel-doc with the implementation
(i.e., in .c files) when possible, not with the function prototype.
Of course, for inline functions or macros in header files, that's
where the kernel-doc has to live.

so we don't need this patch.


> +/***
> + * mutex_trylock - try acquire the mutex, without waiting
> + * @lock: the mutex to be acquired
> + *
> + * Try to acquire the mutex atomically. Returns 1 if the mutex
> + * has been acquired successfully, and 0 on contention.
> + *
> + * NOTE: this function follows the spin_trylock() convention, so
> + * it is negated to the down_trylock() return values! Be careful
> + * about this when converting semaphore users to mutexes.
> + *
> + * This function must not be used in interrupt context. The
> + * mutex must be released by the same task that acquired it.
> */
> extern int fastcall mutex_trylock(struct mutex *lock);
> extern void fastcall mutex_unlock(struct mutex *lock);


---
~Randy
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