Re: [PATCH 11/35] media: s2255: Use refcount_t instead of atomic_t for num_channels

Bryan O'Donoghue
2024-04-23T12:43:54Z

On 15/04/2024 20:34, Ricardo Ribalda wrote:
> Use an API that resembles more the actual use of num_channels.
>
> Found by cocci:
> drivers/media/usb/s2255/s2255drv.c:2362:5-24: WARNING: atomic_dec_and_test variation before object free at line 2363.
> drivers/media/usb/s2255/s2255drv.c:1557:5-24: WARNING: atomic_dec_and_test variation before object free at line 1558.

Hmm, that commit log needs more detail.

"Convert from atomic_t to refcount_t because refcount_t has memory
ordering guarantees which atomic does not, hence the WARNING for the
free after the atomic dec."

Something like that.

I'll leave it up to yourself to decide if this warrants a Fixes:

I don't think so myself because the previous code doesn't seem to matter
to the decrement and free.

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bod