spu_syscalls.c

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/*
 * SPU file system -- system call stubs
 *
 * (C) Copyright IBM Deutschland Entwicklung GmbH 2005
 * (C) Copyright 2006-2007, IBM Corporation
 *
 * Author: Arnd Bergmann <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/module.h>
#include <linux/syscalls.h>
#include <linux/rcupdate.h>

#include <asm/spu.h>

/* protected by rcu */
static struct spufs_calls *spufs_calls;

#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 */

SYSCALL_DEFINE4(spu_create, const char __user *, name, unsigned int, flags,
    umode_t, mode, int, neighbor_fd)
{
    long ret;
    struct spufs_calls *calls;

    calls = spufs_calls_get();
    if (!calls)
        return -ENOSYS;

    if (flags & SPU_CREATE_AFFINITY_SPU) {
        struct fd neighbor = fdget(neighbor_fd);
        ret = -EBADF;
        if (neighbor.file) {
            ret = calls->create_thread(name, flags, mode, neighbor.file);
            fdput(neighbor);
        }
    } else
        ret = calls->create_thread(name, flags, mode, NULL);

    spufs_calls_put(calls);
    return ret;
}

asmlinkage long sys_spu_run(int fd, __u32 __user *unpc, __u32 __user *ustatus)
{
    long ret;
    struct fd arg;
    struct spufs_calls *calls;

    calls = spufs_calls_get();
    if (!calls)
        return -ENOSYS;

    ret = -EBADF;
    arg = fdget(fd);
    if (arg.file) {
        ret = calls->spu_run(arg.file, unpc, ustatus);
        fdput(arg);
    }

    spufs_calls_put(calls);
    return ret;
}

int elf_coredump_extra_notes_size(void)
{
    struct spufs_calls *calls;
    int ret;

    calls = spufs_calls_get();
    if (!calls)
        return 0;

    ret = calls->coredump_extra_notes_size();

    spufs_calls_put(calls);

    return ret;
}

int elf_coredump_extra_notes_write(struct file *file, loff_t *foffset)
{
    struct spufs_calls *calls;
    int ret;

    calls = spufs_calls_get();
    if (!calls)
        return 0;

    ret = calls->coredump_extra_notes_write(file, foffset);

    spufs_calls_put(calls);

    return ret;
}

void notify_spus_active(void)
{
    struct spufs_calls *calls;

    calls = spufs_calls_get();
    if (!calls)
        return;

    calls->notify_spus_active();
    spufs_calls_put(calls);

    return;
}

int register_spu_syscalls(struct spufs_calls *calls)
{
    if (spufs_calls)
        return -EBUSY;

    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);
    rcu_assign_pointer(spufs_calls, NULL);
    synchronize_rcu();
}
EXPORT_SYMBOL_GPL(unregister_spu_syscalls);