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libap: use custom wait time for file locks

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If many invocations of mdevctl occur simultaneously (as can happen with
libvirt) then waiting for 5-60 seconds per lock retry is simply too long.
Anticipating this possibility, retry more frequently but also attempt
significantly more retries than before.

Reported-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Reviewed-by: Boris Fiuczynski <fiuczy@linux.ibm.com>
Reviewed-by: Marc Hartmayer <marc@linux.ibm.com>
Tested-by: Marc Hartmayer <marc@linux.ibm.com>
Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
This commit is contained in:
Matthew Rosato
2024-04-11 14:36:34 -04:00
committed by Steffen Eiden
parent f5f806af06
commit 474c6adf8f
2 changed files with 27 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
include/lib/ap.h
View File

@@ -21,7 +21,9 @@
#define AP_UDEV_FILE "/etc/udev/rules.d/41-ap.rules"
#define AP_LOCKFILE "/run/lock/s390apconfig.lock"
#define AP_LOCK_RETRIES 15
#define AP_LOCK_RETRIES 3000
#define AP_LOCK_DELAY_US 30000 /* wait at least 30ms between lock retries */
#define AP_LOCK_VARIANCE_US 3000 /* or as much as 33ms */
/* apmask and aqmask are each represented as 67 character strings with:
* '0x' leading characters

26
libap/ap.c
View File

@@ -11,12 +11,15 @@
#include <dirent.h>
#include <err.h>
#include <errno.h>
#include <limits.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/time.h>
#ifdef HAVE_JSONC
#include <json-c/json.h>
@@ -698,6 +701,20 @@ void ap_list_remove_all(struct util_list *list)
}
}
static unsigned int random_delay(void)
{
static bool libap_seed = true;
struct timeval t;
if (libap_seed) {
gettimeofday(&t, NULL);
srand((unsigned int)((t.tv_sec + t.tv_usec) % UINT_MAX));
libap_seed = false;
}
return AP_LOCK_DELAY_US + (rand() % AP_LOCK_VARIANCE_US);
}
/**
* Acquire the ap config lock using this Process ID
*
@@ -707,7 +724,9 @@ void ap_list_remove_all(struct util_list *list)
*/
int ap_get_lock(void)
{
return util_lockfile_lock(AP_LOCKFILE, AP_LOCK_RETRIES);
unsigned int delay = random_delay();
return util_lockfile_lock_cw(AP_LOCKFILE, AP_LOCK_RETRIES, delay, delay);
}
/**
@@ -719,7 +738,10 @@ int ap_get_lock(void)
*/
int ap_get_lock_callout(void)
{
return util_lockfile_parent_lock(AP_LOCKFILE, AP_LOCK_RETRIES);
unsigned int delay = random_delay();
return util_lockfile_parent_lock_cw(AP_LOCKFILE, AP_LOCK_RETRIES, delay,
delay);
}
/**