commit dee15756bcb287ccf39a904be07c90107b13844b
Author: Laurent Dufour <ldufour@linux.ibm.com>
Date:   Wed May 3 10:50:15 2023 +0200

    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>
    Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com>

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",