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3a7d2fd16c
Lockdep complains about a possible deadlock between mount and unlink (which is technically impossible), but fixing this improves possible future multiple-backend support, and keeps locking in the right order. The lockdep warning could be triggered by unlinking a file in the pstore filesystem: -> #1 (&sb->s_type->i_mutex_key#14){++++++}: lock_acquire+0xc9/0x220 down_write+0x3f/0x70 pstore_mkfile+0x1f4/0x460 pstore_get_records+0x17a/0x320 pstore_fill_super+0xa4/0xc0 mount_single+0x89/0xb0 pstore_mount+0x13/0x20 mount_fs+0xf/0x90 vfs_kern_mount+0x66/0x170 do_mount+0x190/0xd50 SyS_mount+0x90/0xd0 entry_SYSCALL_64_fastpath+0x1c/0xb1 -> #0 (&psinfo->read_mutex){+.+.+.}: __lock_acquire+0x1ac0/0x1bb0 lock_acquire+0xc9/0x220 __mutex_lock+0x6e/0x990 mutex_lock_nested+0x16/0x20 pstore_unlink+0x3f/0xa0 vfs_unlink+0xb5/0x190 do_unlinkat+0x24c/0x2a0 SyS_unlinkat+0x16/0x30 entry_SYSCALL_64_fastpath+0x1c/0xb1 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&sb->s_type->i_mutex_key#14); lock(&psinfo->read_mutex); lock(&sb->s_type->i_mutex_key#14); lock(&psinfo->read_mutex); Reported-by: Marta Lofstedt <marta.lofstedt@intel.com> Reported-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: Namhyung Kim <namhyung@kernel.org>
35 lines
940 B
C
35 lines
940 B
C
#ifndef __PSTORE_INTERNAL_H__
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#define __PSTORE_INTERNAL_H__
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#include <linux/types.h>
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#include <linux/time.h>
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#include <linux/pstore.h>
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#ifdef CONFIG_PSTORE_FTRACE
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extern void pstore_register_ftrace(void);
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extern void pstore_unregister_ftrace(void);
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#else
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static inline void pstore_register_ftrace(void) {}
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static inline void pstore_unregister_ftrace(void) {}
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#endif
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#ifdef CONFIG_PSTORE_PMSG
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extern void pstore_register_pmsg(void);
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extern void pstore_unregister_pmsg(void);
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#else
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static inline void pstore_register_pmsg(void) {}
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static inline void pstore_unregister_pmsg(void) {}
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#endif
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extern struct pstore_info *psinfo;
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extern void pstore_set_kmsg_bytes(int);
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extern void pstore_get_records(int);
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extern void pstore_get_backend_records(struct pstore_info *psi,
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struct dentry *root, int quiet);
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extern int pstore_mkfile(struct dentry *root,
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struct pstore_record *record);
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extern bool pstore_is_mounted(void);
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#endif
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