File lparstat-Fix-offline-threads-uninitialized-entr... of Package powerpc-utils.33616

Overview Repositories Revisions Requests Users Attributes Meta

File lparstat-Fix-offline-threads-uninitialized-entries.patch of Package powerpc-utils.33616

From 7a5625f2bc012fbbf0cd8384cb4e7761c5de3bb7 Mon Sep 17 00:00:00 2001
From: Laurent Dufour <ldufour@linux.ibm.com>
Date: Tue, 2 May 2023 19:59:27 +0200
Subject: [PATCH 3/3] lparstat: Fix offline threads uninitialized entries

When some threads are offline, lparstat -E is failing like that:

$ ppc64_cpu --info # CPU 20 is offline
Core   0:    0*    1*    2*    3*    4*    5*    6*    7*
Core   1:    8*    9*   10*   11*   12*   13*   14*   15*
Core   2:   16*   17*   18*   19*   20    21*   22*   23*
Core   3:   24*   25*   26*   27*   28*   29*   30*   31*
Core   4:   32*   33*   34*   35*   36*   37*   38*   39*
Core   5:   40*   41*   42*   43*   44*   45*   46*   47*
$ lparstat -E
Failed to read /sys/devices/system/cpu/cpu0/spurr

The message is complaining about CPU0 but the real issue is that in
parse_sysfs_values() the test cpu_sysfs_fds[i].spurr >= 0 is valid even if
the entry has not been initialized (cpu_sysfs_fds is alloc cleared). So
if the number of threads online seen in assign_cpu_sysfs_fds is lower than
threads_in_system, the loop in parse_sysfs_values() will read uninitialized
entry, where .cpu=0.

To prevent that, unset entries in the cpu_sysfs_fds should have the spurr
fd set to -1.

Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
---
 src/lparstat.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/lparstat.c b/src/lparstat.c
index a9e7bce..d2fdb3f 100644
--- a/src/lparstat.c
+++ b/src/lparstat.c
@@ -163,6 +163,10 @@ static int assign_cpu_sysfs_fds(int threads_in_system)
 		cpu_idx++;
 	}
 
+	/* Mark extra slots for offline threads unset, see parse_sysfs_values */
+	for (; cpu_idx < threads_in_system; cpu_idx++)
+		cpu_sysfs_fds[cpu_idx].spurr = -1;
+
 	return 0;
 error:
 	fprintf(stderr, "Failed to open %s: %s\n",
-- 
2.40.1

Places

File lparstat-Fix-offline-threads-uninitialized-entries.patch of Package powerpc-utils.33616

Places