From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ingo Molnar Date: Thu, 20 Jan 2005 16:44:28 +0000 Subject: Re: [patch 1/3] spinlock fix #1, *_can_lock() primitives Message-Id: <20050120164428.GA16342@elte.hu> List-Id: References: <16878.9678.73202.771962@wombat.chubb.wattle.id.au> <20050119092013.GA2045@elte.hu> <16878.54402.344079.528038@cargo.ozlabs.ibm.com> <20050120023445.GA3475@taniwha.stupidest.org> <20050119190104.71f0a76f.akpm@osdl.org> <20050120031854.GA8538@taniwha.stupidest.org> <16879.29449.734172.893834@wombat.chubb.wattle.id.au> <20050120160839.GA13067@elte.hu> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Linus Torvalds Cc: Peter Chubb , Chris Wedgwood , Andrew Morton , paulus@samba.org, linux-kernel@vger.kernel.org, tony.luck@intel.com, dsw@gelato.unsw.edu.au, benh@kernel.crashing.org, linux-ia64@vger.kernel.org, hch@infradead.org, wli@holomorphy.com, jbarnes@sgi.com * Linus Torvalds wrote: > I can do ppc64 myself, can others fix the other architectures (Ingo, > shouldn't the UP case have the read/write_can_lock() cases too? And > wouldn't you agree that it makes more sense to have the rwlock test > variants in asm/rwlock.h?): this one adds it to x64. (untested at the moment) This patch assumes that we are nuking rwlock_is_locked and that there is at least a s/rwlock_is_locked/!write_can_lock/ done to kernel/exit.c. Ingo Signed-off-by: Ingo Molnar --- linux/include/asm-x86_64/spinlock.h.orig +++ linux/include/asm-x86_64/spinlock.h @@ -161,7 +161,23 @@ typedef struct { #define rwlock_init(x) do { *(x) = RW_LOCK_UNLOCKED; } while(0) -#define rwlock_is_locked(x) ((x)->lock != RW_LOCK_BIAS) +/** + * read_can_lock - would read_trylock() succeed? + * @lock: the rwlock in question. + */ +static inline int read_can_lock(rwlock_t *rw) +{ + return rw->lock > 0; +} + +/** + * write_can_lock - would write_trylock() succeed? + * @lock: the rwlock in question. + */ +static inline int write_can_lock(rwlock_t *rw) +{ + return rw->lock = RW_LOCK_BIAS; +} /* * On x86, we implement read-write locks as a 32-bit counter