linux-kernel - [PATCH] block/blk-iocost (gcc13): cast enum members to int in prints

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Date:   Mon, 31 Oct 2022 12:45:20 +0100
From:   "Jiri Slaby (SUSE)" <jirislaby@...nel.org>
To:     tj@...nel.org
Cc:     linux-kernel@...r.kernel.org,
        "Jiri Slaby (SUSE)" <jirislaby@...nel.org>,
        Martin Liska <mliska@...e.cz>,
        Josef Bacik <josef@...icpanda.com>,
        Jens Axboe <axboe@...nel.dk>, cgroups@...r.kernel.org,
        linux-block@...r.kernel.org
Subject: [PATCH] block/blk-iocost (gcc13): cast enum members to int in prints

Since gcc13, each member of an enum has the same type as the enum [1]. And
that is inherited from its members. Provided:
  VTIME_PER_SEC_SHIFT     = 37,
  VTIME_PER_SEC           = 1LLU << VTIME_PER_SEC_SHIFT,
the named type is unsigned long.

This generates warnings with gcc-13:
  block/blk-iocost.c: In function 'ioc_weight_prfill':
  block/blk-iocost.c:3037:37: error: format '%u' expects argument of type 'unsigned int', but argument 4 has type 'long unsigned int'

  block/blk-iocost.c: In function 'ioc_weight_show':
  block/blk-iocost.c:3047:34: error: format '%u' expects argument of type 'unsigned int', but argument 3 has type 'long unsigned int'

Cast the enum members to int when printing them.

Alternatively, we can cast them to ulong (to silence gcc < 12) and use %lu.
Alternatively, we can move VTIME_PER_SEC away from the enum.

[1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=36113

Cc: Martin Liska <mliska@...e.cz>
Cc: Tejun Heo <tj@...nel.org>
Cc: Josef Bacik <josef@...icpanda.com>
Cc: Jens Axboe <axboe@...nel.dk>
Cc: cgroups@...r.kernel.org
Cc: linux-block@...r.kernel.org
Signed-off-by: Jiri Slaby (SUSE) <jirislaby@...nel.org>
---
 block/blk-iocost.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index f01359906c83..a257ba17183b 100644
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -3034,7 +3034,8 @@ static u64 ioc_weight_prfill(struct seq_file *sf, struct blkg_policy_data *pd,
 	struct ioc_gq *iocg = pd_to_iocg(pd);
 
 	if (dname && iocg->cfg_weight)
-		seq_printf(sf, "%s %u\n", dname, iocg->cfg_weight / WEIGHT_ONE);
+		seq_printf(sf, "%s %d\n", dname,
+				iocg->cfg_weight / (int)WEIGHT_ONE);
 	return 0;
 }
 
@@ -3044,7 +3045,8 @@ static int ioc_weight_show(struct seq_file *sf, void *v)
 	struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
 	struct ioc_cgrp *iocc = blkcg_to_iocc(blkcg);
 
-	seq_printf(sf, "default %u\n", iocc->dfl_weight / WEIGHT_ONE);
+	seq_printf(sf, "default %d\n",
+			iocc->dfl_weight / (int)WEIGHT_ONE);
 	blkcg_print_blkgs(sf, blkcg, ioc_weight_prfill,
 			  &blkcg_policy_iocost, seq_cft(sf)->private, false);
 	return 0;
-- 
2.38.1