Revision 9107c89e269d2738019861bb518e3d59bef01781 authored by Peter Zijlstra on 24 February 2016, 17:45:45 UTC, committed by Ingo Molnar on 25 February 2016, 07:42:34 UTC
perf_install_in_context() relies upon the context switch hooks to have scheduled in events when the IPI misses its target -- after all, if the task has moved from the CPU (or wasn't running at all), it will have to context switch to run elsewhere. This however doesn't appear to be happening. It is possible for the IPI to not happen (task wasn't running) only to later observe the task running with an inactive context. The only possible explanation is that the context switch hooks are not called. Therefore put in a sync_sched() after toggling the jump_label to guarantee all CPUs will have them enabled before we install an event. A simple if (0->1) sync_sched() will not in fact work, because any further increment can race and complete before the sync_sched(). Therefore we must jump through some hoops. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: dvyukov@google.com Cc: eranian@google.com Cc: oleg@redhat.com Cc: panand@redhat.com Cc: sasha.levin@oracle.com Cc: vince@deater.net Link: http://lkml.kernel.org/r/20160224174947.980211985@infradead.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
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internal.h
/* fs/ internal definitions
*
* Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* 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 of the License, or (at your option) any later version.
*/
struct super_block;
struct file_system_type;
struct linux_binprm;
struct path;
struct mount;
struct shrink_control;
/*
* block_dev.c
*/
#ifdef CONFIG_BLOCK
extern void __init bdev_cache_init(void);
extern int __sync_blockdev(struct block_device *bdev, int wait);
#else
static inline void bdev_cache_init(void)
{
}
static inline int __sync_blockdev(struct block_device *bdev, int wait)
{
return 0;
}
#endif
/*
* buffer.c
*/
extern void guard_bio_eod(int rw, struct bio *bio);
/*
* char_dev.c
*/
extern void __init chrdev_init(void);
/*
* namei.c
*/
extern int user_path_mountpoint_at(int, const char __user *, unsigned int, struct path *);
extern int vfs_path_lookup(struct dentry *, struct vfsmount *,
const char *, unsigned int, struct path *);
/*
* namespace.c
*/
extern void *copy_mount_options(const void __user *);
extern char *copy_mount_string(const void __user *);
extern struct vfsmount *lookup_mnt(struct path *);
extern int finish_automount(struct vfsmount *, struct path *);
extern int sb_prepare_remount_readonly(struct super_block *);
extern void __init mnt_init(void);
extern int __mnt_want_write(struct vfsmount *);
extern int __mnt_want_write_file(struct file *);
extern void __mnt_drop_write(struct vfsmount *);
extern void __mnt_drop_write_file(struct file *);
/*
* fs_struct.c
*/
extern void chroot_fs_refs(const struct path *, const struct path *);
/*
* file_table.c
*/
extern struct file *get_empty_filp(void);
/*
* super.c
*/
extern int do_remount_sb(struct super_block *, int, void *, int);
extern bool trylock_super(struct super_block *sb);
extern struct dentry *mount_fs(struct file_system_type *,
int, const char *, void *);
extern struct super_block *user_get_super(dev_t);
/*
* open.c
*/
struct open_flags {
int open_flag;
umode_t mode;
int acc_mode;
int intent;
int lookup_flags;
};
extern struct file *do_filp_open(int dfd, struct filename *pathname,
const struct open_flags *op);
extern struct file *do_file_open_root(struct dentry *, struct vfsmount *,
const char *, const struct open_flags *);
extern long do_handle_open(int mountdirfd,
struct file_handle __user *ufh, int open_flag);
extern int open_check_o_direct(struct file *f);
extern int vfs_open(const struct path *, struct file *, const struct cred *);
/*
* inode.c
*/
extern long prune_icache_sb(struct super_block *sb, struct shrink_control *sc);
extern void inode_add_lru(struct inode *inode);
/*
* fs-writeback.c
*/
extern void inode_io_list_del(struct inode *inode);
extern long get_nr_dirty_inodes(void);
extern void evict_inodes(struct super_block *);
extern int invalidate_inodes(struct super_block *, bool);
/*
* dcache.c
*/
extern struct dentry *__d_alloc(struct super_block *, const struct qstr *);
extern int d_set_mounted(struct dentry *dentry);
extern long prune_dcache_sb(struct super_block *sb, struct shrink_control *sc);
/*
* read_write.c
*/
extern int rw_verify_area(int, struct file *, const loff_t *, size_t);
/*
* pipe.c
*/
extern const struct file_operations pipefifo_fops;
/*
* fs_pin.c
*/
extern void group_pin_kill(struct hlist_head *p);
extern void mnt_pin_kill(struct mount *m);
/*
* fs/nsfs.c
*/
extern struct dentry_operations ns_dentry_operations;
/*
* fs/ioctl.c
*/
extern int do_vfs_ioctl(struct file *file, unsigned int fd, unsigned int cmd,
unsigned long arg);
extern long vfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
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