Messages in this thread | | | Date | Mon, 27 Jun 2022 22:51:38 +0800 (CST) | From | "Liang He" <> | Subject | Re:Re: [PATCH] firmware: Hold a reference for of_find_compatible_node() |
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At 2022-06-27 22:09:43, "Greg KH" <gregkh@linuxfoundation.org> wrote: >On Tue, Jun 21, 2022 at 11:26:25AM +0800, Liang He wrote: >> In of_register_trusted_foundations(), we need to hold the reference >> returned by of_find_compatible_node() and then use it to call >> of_node_put() for refcount balance. >> >> Signed-off-by: Liang He <windhl@126.com> >> --- >> include/linux/firmware/trusted_foundations.h | 8 ++++++-- >> 1 file changed, 6 insertions(+), 2 deletions(-) >> >> diff --git a/include/linux/firmware/trusted_foundations.h b/include/linux/firmware/trusted_foundations.h >> index be5984bda592..399471c2f1c7 100644 >> --- a/include/linux/firmware/trusted_foundations.h >> +++ b/include/linux/firmware/trusted_foundations.h >> @@ -71,12 +71,16 @@ static inline void register_trusted_foundations( >> >> static inline void of_register_trusted_foundations(void) >> { >> + struct device_node *np = of_find_compatible_node(NULL, NULL, "tlm,trusted-foundations"); >> + >> + of_node_put(np); >> + if (!np) > >While this is technically correct, you are now checking to see if this >points to a memory location that you no longer know what it really >belongs to. C will let you do this, but it might be nicer to fix it up >properly so it doesn't look like this. > >thanks, > >greg k-h
Hi,Greg KH,
Thanks very much for your effort to review my patch.
In fact, I have reported a commit for this kind of 'check-after-put' coding style: https://lore.kernel.org/all/20220617112636.4041671-1-windhl@126.com/
But I have been told to keep such style and I think the explanation is also reasonable. So when I make this patch, I am indeed confused what I should write.
Finally, I think it is better to be consistent with current coding style so I chose this 'check-after-put' style.
But if you think it is better to use a normal order, i.e., check-then-put, I am, of cause, very happy to send a new patch for this bug and I will also keep to use this coding style in future.
Thanks again.
Liang
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