linux-kernel - staging: emxx_udc question on i_write

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Message-ID: <Y2NtTXwMef0kp01s@qemulion>
Date:   Thu, 3 Nov 2022 12:57:09 +0530
From:   Deepak R Varma <drv@...lo.com>
To:     outreachy@...ts.linux.dev,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: staging: emxx_udc question on i_write_length datatype

Hello,
While reviewing this [1] coccicheck warning, I observed something that concerned
me. The variable i_write_length is declared to be of u32 type. Later it is
assigned a value DMA_MAX_COUNT * mpkt; which is 256 * u32;

I am unable to estimate if mpkt (or max packet size) can attain value greater
than 16777215 in which case the result will overflow the 32 bits of
i_write_length. Is it safe to make i_write_length to be a u64?

[1] drivers/staging/emxx_udc/emxx_udc.c:1007:28-29: WARNING opportunity for min()