• Stephen Boyd's avatar
    lib: atomic64: Initialize locks statically to fix early users · fcc16882
    Stephen Boyd authored
    The atomic64 library uses a handful of static spin locks to implement
    atomic 64-bit operations on architectures without support for atomic
    64-bit instructions.
    
    Unfortunately, the spinlocks are initialized in a pure initcall and that
    is too late for the vfs namespace code which wants to use atomic64
    operations before the initcall is run.
    
    This became a problem as of commit 8823c079: "vfs: Add setns support
    for the mount namespace".
    
    This leads to BUG messages such as:
    
      BUG: spinlock bad magic on CPU#0, swapper/0/0
       lock: atomic64_lock+0x240/0x400, .magic: 00000000, .owner: <none>/-1, .owner_cpu: 0
        do_raw_spin_lock+0x158/0x198
        _raw_spin_lock_irqsave+0x4c/0x58
        atomic64_add_return+0x30/0x5c
        alloc_mnt_ns.clone.14+0x44/0xac
        create_mnt_ns+0xc/0x54
        mnt_init+0x120/0x1d4
        vfs_caches_init+0xe0/0x10c
        start_kernel+0x29c/0x300
    
    coming out early on during boot when spinlock debugging is enabled.
    
    Fix this by initializing the spinlocks statically at compile time.
    Reported-and-tested-by: 's avatarVaibhav Bedia <vaibhav.bedia@ti.com>
    Tested-by: 's avatarTony Lindgren <tony@atomide.com>
    Cc: Eric W. Biederman <ebiederm@xmission.com>
    Signed-off-by: 's avatarStephen Boyd <sboyd@codeaurora.org>
    Signed-off-by: 's avatarLinus Torvalds <torvalds@linux-foundation.org>
    fcc16882
atomic64.c 4.17 KB