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udev-node: add random delay on conflict in updating device node symlink

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To make multiple workers not update the same device node symlink
simultaneously.
This commit is contained in:
Yu Watanabe 2021-09-01 04:34:48 +09:00
parent 8424da2de8
commit 0063fa23a1
1 changed files with 12 additions and 0 deletions
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12
src/udev/udev-node.c
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@ -20,12 +20,14 @@
#include "mkdir.h"
#include "parse-util.h"
#include "path-util.h"
#include "random-util.h"
#include "selinux-util.h"
#include "smack-util.h"
#include "stat-util.h"
#include "stdio-util.h"
#include "string-util.h"
#include "strxcpyx.h"
#include "time-util.h"
#include "udev-node.h"
#include "user-util.h"
@ -33,6 +35,8 @@
#define LINK_UPDATE_MAX_RETRIES 128
#define CREATE_STACK_LINK_MAX_RETRIES 128
#define UPDATE_TIMESTAMP_MAX_RETRIES 128
#define MAX_RANDOM_DELAY (250 * USEC_PER_MSEC)
#define MIN_RANDOM_DELAY ( 50 * USEC_PER_MSEC)
#define UDEV_NODE_HASH_KEY SD_ID128_MAKE(b9,6a,f1,ce,40,31,44,1a,9e,19,ec,8b,ae,f3,e3,2f)
static int create_symlink(const char *target, const char *slink) {
@ -447,6 +451,14 @@ static int link_update(sd_device *dev, const char *slink_in, bool add) {
_cleanup_free_ char *target = NULL;
struct stat st1 = {}, st2 = {};
if (i > 0) {
usec_t delay = MIN_RANDOM_DELAY + random_u64_range(MAX_RANDOM_DELAY - MIN_RANDOM_DELAY);
log_device_debug(dev, "Directory %s was updated, retrying to update devlink %s after %s.",
dirname, slink, FORMAT_TIMESPAN(delay, USEC_PER_MSEC));
(void) usleep(delay);
}
if (stat(dirname, &st1) < 0 && errno != ENOENT)
return log_device_debug_errno(dev, errno, "Failed to stat %s: %m", dirname);