* Oleg Nesterov <o...@redhat.com> [2012-11-23 21:28:06]:
> register/unregister verifies that inode/uc != NULL. For what?
> This really looks like "hide the potential problem", the caller
> should pass the valid data.
>
Agree that users should pass valid data.
I do understand that we expect the users to be knowledge-able.
Also users are routed thro in-kernel api that does this check.
However from an api perspective, if a user passes invalid data, do we
want the system to crash.
Esp if kernel can identify that users has indeed passed wrong info. I do agree
that users can still pass invalid data that kernel maynot be able to
identify in most cases.
> register() also checks uc->next == NULL, probably to prevent the
> double-register but the caller can do other stupid/wrong things.
Users can surely do more stupid things. But this is again something that
kernel can identify. By allowing a double-register of a consumer, thats
already registered, we might end up allowing circular loop of consumers.
> If we do this check, then we should document that uc->next should
> be cleared before register() and add BUG_ON().
>
> Also add the small comment about the i_size_read() check.
>
> Signed-off-by: Oleg Nesterov <o...@redhat.com>
> ---
> kernel/events/uprobes.c | 7 +------
> 1 files changed, 1 insertions(+), 6 deletions(-)
>
> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
> index 13b247c..d8e930a 100644
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -844,9 +844,7 @@ int uprobe_register(struct inode *inode, loff_t offset,
> struct uprobe_consumer *
> struct uprobe *uprobe;
> int ret;
>
> - if (!inode || !uc || uc->next)
> - return -EINVAL;
> -
> + /* Racy, just to catch the obvious mistakes */
> if (offset > i_size_read(inode))
> return -EINVAL;
>
> @@ -883,9 +881,6 @@ void uprobe_unregister(struct inode *inode, loff_t
> offset, struct uprobe_consume
> {
> struct uprobe *uprobe;
>
> - if (!inode || !uc)
> - return;
> -
> uprobe = find_uprobe(inode, offset);
> if (!uprobe)
> return;
> --
> 1.5.5.1
>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
