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From 185ec4397e61ad00dd68c841e15eaa8629eb9514 Mon Sep 17 00:00:00 2001
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From: Coly Li <colyli@suse.de>
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Date: Sat, 11 Apr 2020 00:24:46 +0800
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Subject: [RHEL7.9 PATCH 68/71] Monitor: improve check_one_sharer() for
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checking duplicated process
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When running mdadm monitor with scan mode, only one autorebuild process
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is allowed. check_one_sharer() checks duplicated process by following
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steps,
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1) Read autorebuild.pid file,
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- if file does not exist, no duplicated process, go to 3).
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- if file exists, continue to next step.
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2) Read pid number from autorebuild.pid file, then check procfs pid
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directory /proc/<PID>,
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- if the directory does not exist, no duplicated process, go to 3)
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- if the directory exists, print error message for duplicated process
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and exit this mdadm.
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3) Write current pid into autorebuild.pid file, continue to monitor in
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scan mode.
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The problem for the above step 2) is, if after system reboots and
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another different process happens to have exact same pid number which
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autorebuild.pid file records, check_one_sharer() will treat it as a
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duplicated mdadm process and returns error with message "Only one
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autorebuild process allowed in scan mode, aborting".
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This patch tries to fix the above same-pid-but-different-process issue
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by one more step to check the process command name,
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1) Read autorebuild.pid file
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- if file does not exist, no duplicated process, go to 4).
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- if file exists, continue to next step.
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2) Read pid number from autorebuild.pid file, then check procfs file
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comm with the specific pid directory /proc/<PID>/comm
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- if the file does not exit, it means the directory /proc/<PID> does
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not exist, go to 4)
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- if the file exits, continue next step
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3) Read process command name from /proc/<PIC>/comm, compare the command
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name with "mdadm" process name,
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- if not equal, no duplicated process, goto 4)
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- if strings are equal, print error message for duplicated process
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and exit this mdadm.
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4) Write current pid into autorebuild.pid file, continue to monitor in
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scan mode.
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Now check_one_sharer() returns error for duplicated process only when
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the recorded pid from autorebuild.pid exists, and the process has exact
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same command name as "mdadm".
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Reported-by: Shinkichi Yamazaki <shinkichi.yamazaki@suse.com>
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Signed-off-by: Coly Li <colyli@suse.de>
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Signed-off-by: Jes Sorensen <jsorensen@fb.com>
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---
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Monitor.c | 32 ++++++++++++++++++++------------
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1 file changed, 20 insertions(+), 12 deletions(-)
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diff --git a/Monitor.c b/Monitor.c
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index b527165..2d6b3b9 100644
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--- a/Monitor.c
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+++ b/Monitor.c
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@@ -301,26 +301,34 @@ static int make_daemon(char *pidfile)
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static int check_one_sharer(int scan)
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{
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- int pid, rv;
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+ int pid;
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+ FILE *comm_fp;
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FILE *fp;
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- char dir[20];
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+ char comm_path[100];
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char path[100];
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- struct stat buf;
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+ char comm[20];
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+
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sprintf(path, "%s/autorebuild.pid", MDMON_DIR);
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fp = fopen(path, "r");
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if (fp) {
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if (fscanf(fp, "%d", &pid) != 1)
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pid = -1;
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- sprintf(dir, "/proc/%d", pid);
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- rv = stat(dir, &buf;;
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- if (rv != -1) {
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- if (scan) {
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- pr_err("Only one autorebuild process allowed in scan mode, aborting\n");
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- fclose(fp);
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- return 1;
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- } else {
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- pr_err("Warning: One autorebuild process already running.\n");
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+ snprintf(comm_path, sizeof(comm_path),
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+ "/proc/%d/comm", pid);
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+ comm_fp = fopen(comm_path, "r");
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+ if (comm_fp) {
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+ if (fscanf(comm_fp, "%s", comm) &&
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+ strncmp(basename(comm), Name, strlen(Name)) == 0) {
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+ if (scan) {
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+ pr_err("Only one autorebuild process allowed in scan mode, aborting\n");
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+ fclose(comm_fp);
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+ fclose(fp);
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+ return 1;
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+ } else {
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+ pr_err("Warning: One autorebuild process already running.\n");
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+ }
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}
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+ fclose(comm_fp);
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}
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fclose(fp);
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}
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--
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2.7.5
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