From: Matthew Wilcox <willy@infradead.org>
To: "Darrick J. Wong" <djwong@kernel.org>
Cc: linux-kernel@vger.kernel.org,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
pakki001@umn.edu, gregkh@linuxfoundation.org, arnd@arndb.de
Subject: Re: [PATCH] ics932s401: fix broken handling of errors when word reading fails
Date: Wed, 28 Apr 2021 23:46:24 +0100 [thread overview]
Message-ID: <20210428224624.GD1847222@casper.infradead.org> (raw)
In-Reply-To: <20210428222534.GJ3122264@magnolia>
On Wed, Apr 28, 2021 at 03:25:34PM -0700, Darrick J. Wong wrote:
> In commit b05ae01fdb89, someone tried to make the driver handle i2c read
> errors by simply zeroing out the register contents, but for some reason
> left unaltered the code that sets the cached register value the function
> call return value.
>
> The original patch was authored by a member of the Underhanded
> Mangle-happy Nerds, I'm not terribly surprised. I don't have the
> hardware anymore so I can't test this, but it seems like a pretty
> obvious API usage fix to me...
Not sure why you cc'd linux-fsdevel, but that's how i got to see it ...
> +++ b/drivers/misc/ics932s401.c
> @@ -134,7 +134,7 @@ static struct ics932s401_data *ics932s401_update_device(struct device *dev)
> for (i = 0; i < NUM_MIRRORED_REGS; i++) {
> temp = i2c_smbus_read_word_data(client, regs_to_copy[i]);
> if (temp < 0)
> - data->regs[regs_to_copy[i]] = 0;
> + temp = 0;
> data->regs[regs_to_copy[i]] = temp >> 8;
> }
Looking at a bit more context in this function, shouldn't we rather clear
'sensors_valid'? or does it really make sense to pretend we read zero
(rather than 255) from this register?
But then we'd have to actually check sensors_valid in functions like
calculate_src_freq, and i just don't know if it's worthwhile. Why not
just revert this patch?
next prev parent reply other threads:[~2021-04-28 22:46 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-28 22:25 [PATCH] ics932s401: fix broken handling of errors when word reading fails Darrick J. Wong
2021-04-28 22:46 ` Matthew Wilcox [this message]
2021-04-29 1:03 ` Darrick J. Wong
2021-04-29 1:54 ` Matthew Wilcox
2021-04-29 3:20 ` Theodore Ts'o
2021-04-29 7:12 ` Greg KH
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