linux-kernel - [PATCH][next] bcache: Use 64-bit arithmetic instead of 32-bit

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Message-ID: <20210212125028.GA264620@embeddedor>
Date:   Fri, 12 Feb 2021 06:50:28 -0600
From:   "Gustavo A. R. Silva" <gustavoars@...nel.org>
To:     Coly Li <colyli@...e.de>,
        Kent Overstreet <kent.overstreet@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Christina Jacob <cjacob@...vell.com>,
        Hariprasad Kelam <hkelam@...vell.com>,
        Sunil Goutham <sgoutham@...vell.com>,
        Jesse Brandeburg <jesse.brandeburg@...el.com>
Cc:     linux-bcache@...r.kernel.org, linux-kernel@...r.kernel.org,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>
Subject: [PATCH][next] bcache: Use 64-bit arithmetic instead of 32-bit

Cast multiple variables to (int64_t) in order to give the compiler
complete information about the proper arithmetic to use. Notice that
these variables are being used in contexts that expect expressions of
type int64_t  (64 bit, signed). And currently, such expressions are
being evaluated using 32-bit arithmetic.

Fixes: d0cf9503e908 ("octeontx2-pf: ethtool fec mode support")
Addresses-Coverity-ID: 1501724 ("Unintentional integer overflow")
Addresses-Coverity-ID: 1501725 ("Unintentional integer overflow")
Addresses-Coverity-ID: 1501726 ("Unintentional integer overflow")
Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>
---
 drivers/md/bcache/writeback.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c
index 82d4e0880a99..4fb635c0baa0 100644
--- a/drivers/md/bcache/writeback.c
+++ b/drivers/md/bcache/writeback.c
@@ -110,13 +110,13 @@ static void __update_writeback_rate(struct cached_dev *dc)
 		int64_t fps;
 
 		if (c->gc_stats.in_use <= BCH_WRITEBACK_FRAGMENT_THRESHOLD_MID) {
-			fp_term = dc->writeback_rate_fp_term_low *
+			fp_term = (int64_t)dc->writeback_rate_fp_term_low *
 			(c->gc_stats.in_use - BCH_WRITEBACK_FRAGMENT_THRESHOLD_LOW);
 		} else if (c->gc_stats.in_use <= BCH_WRITEBACK_FRAGMENT_THRESHOLD_HIGH) {
-			fp_term = dc->writeback_rate_fp_term_mid *
+			fp_term = (int64_t)dc->writeback_rate_fp_term_mid *
 			(c->gc_stats.in_use - BCH_WRITEBACK_FRAGMENT_THRESHOLD_MID);
 		} else {
-			fp_term = dc->writeback_rate_fp_term_high *
+			fp_term = (int64_t)dc->writeback_rate_fp_term_high *
 			(c->gc_stats.in_use - BCH_WRITEBACK_FRAGMENT_THRESHOLD_HIGH);
 		}
 		fps = div_s64(dirty, dirty_buckets) * fp_term;
-- 
2.27.0