From 98f06978ffebbec16abdea58489f217229580859 Mon Sep 17 00:00:00 2001 From: Jeremy Kerr Date: Wed, 19 Sep 2007 14:38:12 +1000 Subject: [POWERPC] cell: Unify spufs syscall path At present, a built-in spufs will not use the spufs_calls callbacks, but directly call sys_spu_create. This saves us an indirect branch, but means we have duplicated functions - one for CONFIG_SPU_FS=y and one for =m. This change unifies the spufs syscall path, and provides access to the spufs_calls structure through a get/put pair. At present, the only user of the spufs_calls structure is spu_syscalls.c, but this will facilitate adding the coredump calls later. Everyone likes numbers, right? Here's a before/after comparison with CONFIG_SPU_FS=y, doing spu_create(); close(); 64k times. Before: [jk@cell ~]$ time ./spu_create performing 65536 spu_create calls real 0m24.075s user 0m0.146s sys 0m23.925s After: [jk@cell ~]$ time ./spu_create performing 65536 spu_create calls real 0m24.777s user 0m0.141s sys 0m24.631s So, we're adding around 11us per syscall, at the benefit of having only one syscall path. Signed-off-by: Jeremy Kerr Signed-off-by: Paul Mackerras --- arch/powerpc/platforms/cell/spu_syscalls.c | 108 ++++++++++++++++++----------- 1 file changed, 68 insertions(+), 40 deletions(-) (limited to 'arch/powerpc/platforms/cell/spu_syscalls.c') diff --git a/arch/powerpc/platforms/cell/spu_syscalls.c b/arch/powerpc/platforms/cell/spu_syscalls.c index 027ac32cc63..c0238dd9ff2 100644 --- a/arch/powerpc/platforms/cell/spu_syscalls.c +++ b/arch/powerpc/platforms/cell/spu_syscalls.c @@ -22,42 +22,70 @@ #include #include #include +#include #include -struct spufs_calls spufs_calls = { - .owner = NULL, -}; +/* protected by rcu */ +static struct spufs_calls *spufs_calls; -/* These stub syscalls are needed to have the actual implementation - * within a loadable module. When spufs is built into the kernel, - * this file is not used and the syscalls directly enter the fs code */ +#ifdef CONFIG_SPU_FS_MODULE + +static inline struct spufs_calls *spufs_calls_get(void) +{ + struct spufs_calls *calls = NULL; + + rcu_read_lock(); + calls = rcu_dereference(spufs_calls); + if (calls && !try_module_get(calls->owner)) + calls = NULL; + rcu_read_unlock(); + + return calls; +} + +static inline void spufs_calls_put(struct spufs_calls *calls) +{ + BUG_ON(calls != spufs_calls); + + /* we don't need to rcu this, as we hold a reference to the module */ + module_put(spufs_calls->owner); +} + +#else /* !defined CONFIG_SPU_FS_MODULE */ + +static inline struct spufs_calls *spufs_calls_get(void) +{ + return spufs_calls; +} + +static inline void spufs_calls_put(struct spufs_calls *calls) { } + +#endif /* CONFIG_SPU_FS_MODULE */ asmlinkage long sys_spu_create(const char __user *name, unsigned int flags, mode_t mode, int neighbor_fd) { long ret; - struct module *owner = spufs_calls.owner; struct file *neighbor; int fput_needed; + struct spufs_calls *calls; - ret = -ENOSYS; - if (owner && try_module_get(owner)) { - if (flags & SPU_CREATE_AFFINITY_SPU) { - neighbor = fget_light(neighbor_fd, &fput_needed); - ret = -EBADF; - if (neighbor) { - ret = spufs_calls.create_thread(name, flags, - mode, neighbor); - fput_light(neighbor, fput_needed); - } - } - else { - ret = spufs_calls.create_thread(name, flags, - mode, NULL); + calls = spufs_calls_get(); + if (!calls) + return -ENOSYS; + + if (flags & SPU_CREATE_AFFINITY_SPU) { + ret = -EBADF; + neighbor = fget_light(neighbor_fd, &fput_needed); + if (neighbor) { + ret = calls->create_thread(name, flags, mode, neighbor); + fput_light(neighbor, fput_needed); } - module_put(owner); - } + } else + ret = calls->create_thread(name, flags, mode, NULL); + + spufs_calls_put(calls); return ret; } @@ -66,37 +94,37 @@ asmlinkage long sys_spu_run(int fd, __u32 __user *unpc, __u32 __user *ustatus) long ret; struct file *filp; int fput_needed; - struct module *owner = spufs_calls.owner; + struct spufs_calls *calls; - ret = -ENOSYS; - if (owner && try_module_get(owner)) { - ret = -EBADF; - filp = fget_light(fd, &fput_needed); - if (filp) { - ret = spufs_calls.spu_run(filp, unpc, ustatus); - fput_light(filp, fput_needed); - } - module_put(owner); + calls = spufs_calls_get(); + if (!calls) + return -ENOSYS; + + ret = -EBADF; + filp = fget_light(fd, &fput_needed); + if (filp) { + ret = calls->spu_run(filp, unpc, ustatus); + fput_light(filp, fput_needed); } + + spufs_calls_put(calls); return ret; } int register_spu_syscalls(struct spufs_calls *calls) { - if (spufs_calls.owner) + if (spufs_calls) return -EBUSY; - spufs_calls.create_thread = calls->create_thread; - spufs_calls.spu_run = calls->spu_run; - smp_mb(); - spufs_calls.owner = calls->owner; + rcu_assign_pointer(spufs_calls, calls); return 0; } EXPORT_SYMBOL_GPL(register_spu_syscalls); void unregister_spu_syscalls(struct spufs_calls *calls) { - BUG_ON(spufs_calls.owner != calls->owner); - spufs_calls.owner = NULL; + BUG_ON(spufs_calls->owner != calls->owner); + rcu_assign_pointer(spufs_calls, NULL); + synchronize_rcu(); } EXPORT_SYMBOL_GPL(unregister_spu_syscalls); -- cgit v1.2.3-70-g09d2