linux-kernel - [PATCH 11/14] staging/lustre/ptlrpc: Correctly calculate hrp->hrp

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Date:   Wed,  2 Nov 2016 21:25:01 -0400
From:   Oleg Drokin <green@...uxhacker.ru>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        devel@...verdev.osuosl.org,
        Andreas Dilger <andreas.dilger@...el.com>,
        James Simmons <jsimmons@...radead.org>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Lustre Development List <lustre-devel@...ts.lustre.org>,
        Amir Shehata <amir.shehata@...el.com>,
        Oleg Drokin <green@...uxhacker.ru>
Subject: [PATCH 11/14] staging/lustre/ptlrpc: Correctly calculate hrp->hrp_nthrs

From: Amir Shehata <amir.shehata@...el.com>

cpu_pattern can specify exactly 1 cpu in a partition:
"0[0]". That means CPT0 will have CPU 0. CPU 0 can have
hyperthreading enabled. This combination would result in

weight = cfs_cpu_ht_nsiblings(0);
hrp->hrp_nthrs = cfs_cpt_weight(ptlrpc_hr.hr_cpt_table, i);
hrp->hrp_nthrs /= weight;

evaluating to 0. Where
cfs_cpt_weight(ptlrpc_hr.hr_cpt_table, i) == 1
weight == 2

Therefore, if hrp_nthrs becomes zero, just set it to 1.

Signed-off-by: Amir Shehata <amir.shehata@...el.com>
Reviewed-on: http://review.whamcloud.com/19106
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-8492
Reviewed-by: Liang Zhen <liang.zhen@...el.com>
Reviewed-by: Doug Oucharek <doug.s.oucharek@...el.com>
Reviewed-by: James Simmons <uja.ornl@...oo.com>
Signed-off-by: Oleg Drokin <green@...uxhacker.ru>
---
 drivers/staging/lustre/lustre/ptlrpc/service.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/lustre/lustre/ptlrpc/service.c b/drivers/staging/lustre/lustre/ptlrpc/service.c
index 72f3930..fc754e7 100644
--- a/drivers/staging/lustre/lustre/ptlrpc/service.c
+++ b/drivers/staging/lustre/lustre/ptlrpc/service.c
@@ -2541,8 +2541,9 @@ int ptlrpc_hr_init(void)
 
 		hrp->hrp_nthrs = cfs_cpt_weight(ptlrpc_hr.hr_cpt_table, i);
 		hrp->hrp_nthrs /= weight;
+		if (hrp->hrp_nthrs == 0)
+			hrp->hrp_nthrs = 1;
 
-		LASSERT(hrp->hrp_nthrs > 0);
 		hrp->hrp_thrs =
 			kzalloc_node(hrp->hrp_nthrs * sizeof(*hrt), GFP_NOFS,
 				     cfs_cpt_spread_node(ptlrpc_hr.hr_cpt_table,
-- 
2.7.4