The patch titled
Subject: ipc: convert invalid scenarios to use WARN_ON
has been added to the -mm tree. Its filename is
ipc-convert-invalid-scenarios-to-use-warn_on.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/ipc-convert-invalid-scenarios-to-use-warn_on.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/ipc-convert-invalid-scenarios-to-use-warn_on.patch
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------------------------------------------------------
From: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Subject: ipc: convert invalid scenarios to use WARN_ON
Considering Linus' past rants about the (ab)use of BUG in the kernel, I
took a look at how we deal with such calls in ipc. Given that any errors
or corruption in ipc code are most likely contained within the set of
processes participating in the broken mechanisms, there aren't really many
strong fatal system failure scenarios that would require a BUG call.
Also, if something is seriously wrong, ipc might not be the place for such
a BUG either.
1. For example, recently, a customer hit one of these BUG_ONs in shm
after failing shm_lock(). A busted ID imho does not merit a BUG_ON,
and WARN would have been better.
2. MSG_COPY functionality of posix msgrcv(2) for checkpoint/restore.
I don't see how we can hit this anyway -- at least it should be IS_ERR.
The 'copy' arg from do_msgrcv is always set by calling prepare_copy()
first and foremost. We could also probably drop this check altogether.
Either way, it does not merit a BUG_ON.
3. No ->fault() callback for the fs getting the corresponding page --
seems selfish to make the system unusable.
Signed-off-by: Davidlohr Bueso <dbueso@xxxxxxx>
Cc: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
ipc/msgutil.c | 2 +-
ipc/shm.c | 4 ++--
2 files changed, 3 insertions(+), 3 deletions(-)
diff -puN ipc/msgutil.c~ipc-convert-invalid-scenarios-to-use-warn_on ipc/msgutil.c
--- a/ipc/msgutil.c~ipc-convert-invalid-scenarios-to-use-warn_on
+++ a/ipc/msgutil.c
@@ -123,7 +123,7 @@ struct msg_msg *copy_msg(struct msg_msg
size_t len = src->m_ts;
size_t alen;
- BUG_ON(dst == NULL);
+ WARN_ON(dst == NULL);
if (src->m_ts > dst->m_ts)
return ERR_PTR(-EINVAL);
diff -puN ipc/shm.c~ipc-convert-invalid-scenarios-to-use-warn_on ipc/shm.c
--- a/ipc/shm.c~ipc-convert-invalid-scenarios-to-use-warn_on
+++ a/ipc/shm.c
@@ -159,7 +159,7 @@ static inline struct shmid_kernel *shm_l
* We raced in the idr lookup or with shm_destroy(). Either way, the
* ID is busted.
*/
- BUG_ON(IS_ERR(ipcp));
+ WARN_ON(IS_ERR(ipcp));
return container_of(ipcp, struct shmid_kernel, shm_perm);
}
@@ -393,7 +393,7 @@ static int shm_mmap(struct file *file, s
return ret;
sfd->vm_ops = vma->vm_ops;
#ifdef CONFIG_MMU
- BUG_ON(!sfd->vm_ops->fault);
+ WARN_ON(!sfd->vm_ops->fault);
#endif
vma->vm_ops = &shm_vm_ops;
shm_open(vma);
_
Patches currently in -mm which might be from dave@xxxxxxxxxxxx are
ipc-convert-invalid-scenarios-to-use-warn_on.patch
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