linux-kernel - Re: [PATCH net-next 03/11] rsxx: remove extraneous 'const' qualifier

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Message-ID: <f810a6db9f617208302953c7cf837a8f8dd0e39f.camel@perches.com>
Date:   Thu, 29 Oct 2020 14:35:50 -0700
From:   Joe Perches <joe@...ches.com>
To:     Nick Desaulniers <ndesaulniers@...gle.com>,
        Arnd Bergmann <arnd@...nel.org>
Cc:     Joshua Morris <josh.h.morris@...ibm.com>,
        Philip Kelleher <pjk1939@...ux.ibm.com>,
        Arnd Bergmann <arnd@...db.de>, Jens Axboe <axboe@...nel.dk>,
        Nathan Chancellor <natechancellor@...il.com>,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        linux-block@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
        clang-built-linux <clang-built-linux@...glegroups.com>
Subject: Re: [PATCH net-next 03/11] rsxx: remove extraneous 'const' qualifier

On Thu, 2020-10-29 at 12:34 -0700, Nick Desaulniers wrote:
> On Mon, Oct 26, 2020 at 2:31 PM Arnd Bergmann <arnd@...nel.org> wrote:
> > 
> > From: Arnd Bergmann <arnd@...db.de>
> > 
> > The returned string from rsxx_card_state_to_str is 'const',
> > but the other qualifier doesn't change anything here except
> > causing a warning with 'clang -Wextra':
> > 
> > drivers/block/rsxx/core.c:393:21: warning: 'const' type qualifier on return type has no effect [-Wignored-qualifiers]
> > static const char * const rsxx_card_state_to_str(unsigned int state)
> > 
> > Fixes: f37912039eb0 ("block: IBM RamSan 70/80 trivial changes.")
> > Signed-off-by: Arnd Bergmann <arnd@...db.de>
> 
> Reviewed-by: Nick Desaulniers <ndesaulniers@...gle.com>

Perhaps this should also be converted to avoid any possible
dereference of strings with an invalid state.
---
 drivers/block/rsxx/core.c | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/drivers/block/rsxx/core.c b/drivers/block/rsxx/core.c
index 8799e3bab067..f50b00b4887f 100644
--- a/drivers/block/rsxx/core.c
+++ b/drivers/block/rsxx/core.c
@@ -390,15 +390,27 @@ static irqreturn_t rsxx_isr(int irq, void *pdata)
 }
 
 /*----------------- Card Event Handler -------------------*/
-static const char * const rsxx_card_state_to_str(unsigned int state)
+static const char *rsxx_card_state_to_str(unsigned int state)
 {
 	static const char * const state_strings[] = {
-		"Unknown", "Shutdown", "Starting", "Formatting",
-		"Uninitialized", "Good", "Shutting Down",
-		"Fault", "Read Only Fault", "dStroying"
+		"Unknown",		/* no bit set - all zeros */
+		"Shutdown",		/* BIT(0) */
+		"Starting",		/* BIT(1) */
+		"Formatting",		/* BIT(2) */
+		"Uninitialized",	/* BIT(3) */
+		"Good",			/* BIT(4) */
+		"Shutting Down",	/* BIT(5) */
+		"Fault",		/* BIT(6) */
+		"Read Only Fault",	/* BIT(7) */
+		"Destroying"		/* BIT(8) */
 	};
 
-	return state_strings[ffs(state)];
+	int i = ffs(state);
+
+	if (i >= ARRAY_SIZE(state_strings))
+		return "Invalid state";
+
+	return state_strings[i];
 }
 
 static void card_state_change(struct rsxx_cardinfo *card,