Messages in this thread | | | Date | Mon, 10 Dec 2012 11:49:01 +0530 | From | Srikar Dronamraju <> | Subject | Re: [PATCH 3/7] uprobes: Kill the pointless inode/uc checks in register/unregister |
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* Oleg Nesterov <oleg@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 <oleg@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 >
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