| From fcc16882ac4532aaa644bff444f0c5d6228ba71e Mon Sep 17 00:00:00 2001 |
| From: Stephen Boyd <sboyd@codeaurora.org> |
| Date: Wed, 19 Dec 2012 23:39:48 -0800 |
| Subject: lib: atomic64: Initialize locks statically to fix early users |
| |
| From: Stephen Boyd <sboyd@codeaurora.org> |
| |
| commit fcc16882ac4532aaa644bff444f0c5d6228ba71e upstream. |
| |
| 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 8823c079ba71: "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: Vaibhav Bedia <vaibhav.bedia@ti.com> |
| Tested-by: Tony Lindgren <tony@atomide.com> |
| Cc: Eric W. Biederman <ebiederm@xmission.com> |
| Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> |
| Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| lib/atomic64.c | 17 +++++------------ |
| 1 file changed, 5 insertions(+), 12 deletions(-) |
| |
| --- a/lib/atomic64.c |
| +++ b/lib/atomic64.c |
| @@ -31,7 +31,11 @@ |
| static union { |
| raw_spinlock_t lock; |
| char pad[L1_CACHE_BYTES]; |
| -} atomic64_lock[NR_LOCKS] __cacheline_aligned_in_smp; |
| +} atomic64_lock[NR_LOCKS] __cacheline_aligned_in_smp = { |
| + [0 ... (NR_LOCKS - 1)] = { |
| + .lock = __RAW_SPIN_LOCK_UNLOCKED(atomic64_lock.lock), |
| + }, |
| +}; |
| |
| static inline raw_spinlock_t *lock_addr(const atomic64_t *v) |
| { |
| @@ -173,14 +177,3 @@ int atomic64_add_unless(atomic64_t *v, l |
| return ret; |
| } |
| EXPORT_SYMBOL(atomic64_add_unless); |
| - |
| -static int init_atomic64_lock(void) |
| -{ |
| - int i; |
| - |
| - for (i = 0; i < NR_LOCKS; ++i) |
| - raw_spin_lock_init(&atomic64_lock[i].lock); |
| - return 0; |
| -} |
| - |
| -pure_initcall(init_atomic64_lock); |
