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https://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson
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59d6d39f30
One of the two users of spufs_calls.owner still has a race when calling try_module_get while the module is removed. This makes it use the correct instance of owner. Noticed by Milton Miller. Signed-off-by: Arnd Bergmann <arndb@de.ibm.com> Signed-off-by: Paul Mackerras <paulus@samba.org>
89 lines
2.3 KiB
C
89 lines
2.3 KiB
C
/*
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* SPU file system -- system call stubs
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*
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* (C) Copyright IBM Deutschland Entwicklung GmbH 2005
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*
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* Author: Arnd Bergmann <arndb@de.ibm.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <linux/file.h>
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#include <linux/module.h>
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#include <linux/syscalls.h>
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#include <asm/spu.h>
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struct spufs_calls spufs_calls = {
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.owner = NULL,
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};
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/* These stub syscalls are needed to have the actual implementation
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* within a loadable module. When spufs is built into the kernel,
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* this file is not used and the syscalls directly enter the fs code */
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asmlinkage long sys_spu_create(const char __user *name,
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unsigned int flags, mode_t mode)
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{
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long ret;
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struct module *owner = spufs_calls.owner;
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ret = -ENOSYS;
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if (owner && try_module_get(owner)) {
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ret = spufs_calls.create_thread(name, flags, mode);
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module_put(owner);
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}
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return ret;
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}
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asmlinkage long sys_spu_run(int fd, __u32 __user *unpc, __u32 __user *ustatus)
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{
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long ret;
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struct file *filp;
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int fput_needed;
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struct module *owner = spufs_calls.owner;
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ret = -ENOSYS;
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if (owner && try_module_get(owner)) {
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ret = -EBADF;
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filp = fget_light(fd, &fput_needed);
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if (filp) {
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ret = spufs_calls.spu_run(filp, unpc, ustatus);
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fput_light(filp, fput_needed);
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}
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module_put(owner);
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}
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return ret;
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}
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int register_spu_syscalls(struct spufs_calls *calls)
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{
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if (spufs_calls.owner)
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return -EBUSY;
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spufs_calls.create_thread = calls->create_thread;
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spufs_calls.spu_run = calls->spu_run;
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smp_mb();
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spufs_calls.owner = calls->owner;
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return 0;
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}
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EXPORT_SYMBOL_GPL(register_spu_syscalls);
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void unregister_spu_syscalls(struct spufs_calls *calls)
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{
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BUG_ON(spufs_calls.owner != calls->owner);
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spufs_calls.owner = NULL;
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}
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EXPORT_SYMBOL_GPL(unregister_spu_syscalls);
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