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acae051565
There seems to be a common pattern in the kernel where drivers want to call request_module() from inside a module_init() function. Currently this would deadlock. As a result, several drivers go through hoops like scheduling things via kevent, or creating custom work queues (because kevent can deadlock on them). This patch changes this to use a request_module_nowait() function macro instead, which just fires the modprobe off but doesn't wait for it, and thus avoids the original deadlock entirely. On my laptop this already results in one less kernel thread running.. (Includes Jiri's patch to use enum umh_wait) Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (bool-ified) Cc: Jiri Slaby <jirislaby@gmail.com>
110 lines
3.7 KiB
C
110 lines
3.7 KiB
C
#ifndef __LINUX_KMOD_H__
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#define __LINUX_KMOD_H__
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/*
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* include/linux/kmod.h
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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 of the License, or
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* (at your option) 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/gfp.h>
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#include <linux/stddef.h>
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#include <linux/errno.h>
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#include <linux/compiler.h>
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#define KMOD_PATH_LEN 256
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#ifdef CONFIG_MODULES
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/* modprobe exit status on success, -ve on error. Return value
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* usually useless though. */
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extern int __request_module(bool wait, const char *name, ...) \
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__attribute__((format(printf, 2, 3)));
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#define request_module(mod...) __request_module(true, mod)
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#define request_module_nowait(mod...) __request_module(false, mod)
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#define try_then_request_module(x, mod...) \
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((x) ?: (__request_module(false, mod), (x)))
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#else
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static inline int request_module(const char *name, ...) { return -ENOSYS; }
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static inline int request_module_nowait(const char *name, ...) { return -ENOSYS; }
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#define try_then_request_module(x, mod...) (x)
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#endif
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struct key;
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struct file;
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struct subprocess_info;
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/* Allocate a subprocess_info structure */
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struct subprocess_info *call_usermodehelper_setup(char *path, char **argv,
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char **envp, gfp_t gfp_mask);
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/* Set various pieces of state into the subprocess_info structure */
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void call_usermodehelper_setkeys(struct subprocess_info *info,
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struct key *session_keyring);
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int call_usermodehelper_stdinpipe(struct subprocess_info *sub_info,
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struct file **filp);
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void call_usermodehelper_setcleanup(struct subprocess_info *info,
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void (*cleanup)(char **argv, char **envp));
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enum umh_wait {
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UMH_NO_WAIT = -1, /* don't wait at all */
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UMH_WAIT_EXEC = 0, /* wait for the exec, but not the process */
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UMH_WAIT_PROC = 1, /* wait for the process to complete */
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};
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/* Actually execute the sub-process */
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int call_usermodehelper_exec(struct subprocess_info *info, enum umh_wait wait);
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/* Free the subprocess_info. This is only needed if you're not going
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to call call_usermodehelper_exec */
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void call_usermodehelper_freeinfo(struct subprocess_info *info);
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static inline int
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call_usermodehelper(char *path, char **argv, char **envp, enum umh_wait wait)
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{
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struct subprocess_info *info;
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gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
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info = call_usermodehelper_setup(path, argv, envp, gfp_mask);
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if (info == NULL)
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return -ENOMEM;
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return call_usermodehelper_exec(info, wait);
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}
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static inline int
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call_usermodehelper_keys(char *path, char **argv, char **envp,
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struct key *session_keyring, enum umh_wait wait)
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{
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struct subprocess_info *info;
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gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
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info = call_usermodehelper_setup(path, argv, envp, gfp_mask);
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if (info == NULL)
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return -ENOMEM;
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call_usermodehelper_setkeys(info, session_keyring);
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return call_usermodehelper_exec(info, wait);
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}
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extern void usermodehelper_init(void);
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struct file;
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extern int call_usermodehelper_pipe(char *path, char *argv[], char *envp[],
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struct file **filp);
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extern int usermodehelper_disable(void);
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extern void usermodehelper_enable(void);
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#endif /* __LINUX_KMOD_H__ */
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