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

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@kernel.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


             reply	other threads:[~2021-02-12 13:10 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-12 12:50 Gustavo A. R. Silva [this message]
2021-02-12 14:22 ` [PATCH][next] bcache: Use 64-bit arithmetic instead of 32-bit Coly Li
2021-02-12 15:31   ` David Laight
2021-02-12 16:01     ` Coly Li
2021-02-12 16:42       ` David Laight
2021-02-13 15:41         ` Coly Li

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