Messages in this thread | | | From | Lukas Bulwahn <> | Date | Wed, 19 Jan 2022 08:15:10 +0100 | Subject | Re: [PATCH] tracing: Remove redundant assignment to variable ret |
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On Wed, Jan 19, 2022 at 5:18 AM Yuntao Wang <ytcoode@gmail.com> wrote: > > On Mon, Jan 17, 2022 at 3:47 PM Lukas Bulwahn <lukas.bulwahn@gmail.com> wrote: > > Dear Yuntao, > > > > > > when you consider removing dead-store assignments guided by some static > > analyzer, you need to check if the code you are looking at is actually > > missing an error-handling branch. > > > > In this case, ftrace_process_locs() may return -ENOMEM, and the caller > > needs to appropriately deal with this error return code. Your patch > > does not change the code at all, i.e., the compiled object code is the > > same as after the patch as before. > > > > Think about how to deal appropriately with the -ENOMEM return in this > > caller and submit a patch that implements the right error-handling > > branch or argue in your commit message why that is not needed at all. > > > > If you do not understand or cannot check such basic code properties for > > dead-store assignments, it might be better to work on some other aspect > > and area of the kernel repository. E.g., the kernel documentation build > > also has a few warnings that deserve patches to be fixed. > > > > > > Best regards, > > > > Lukas > > Dear Lukas, > > Thanks for your reply. > > Actually, I had read the source code carefully and noticed the possible > error return code -ENOMEM of the ftrace_process_locs() function. > > At first I was going to implement an error-handling branch as you said, > but after digging into more details, I discovered: > > - The ftrace_init() function did not handle the error return code of the ftrace_process_locs() function since the first version. > - The ftrace_module_init() function did not handle it either. >
This is certainly important information on the rationale, and hence, this needs to go into the commit message explaining why you propose this change.
Now, you should also explain: why do you consider it not a problem that this error situation -ENOMEM is not handled by the caller?
And if so, why should ftrace_process_locs() even return an error code if this error return is not considered?
Your commit message should really explain this reasoning.
> To keep consistent with the existing code, I just removed the assignment > in that patch. > > Maybe we should deal with the error return code more appropriately, > at least print some warnings? >
This might be one way of dealing with it.
Lukas
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