The patch titled
getdelays.c: add a USR1 signal handler
has been added to the -mm tree. Its filename is
getdelaysc-add-a-usr1-signal-handler.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: getdelays.c: add a USR1 signal handler
From: Scott Wiersdorf <scott@xxxxxxxxxxxx>
Add a USR1 signal handler to getdelays.c, which causes getdelays to close
its logfile and reopen it (if '-w logfile' is specified). This is useful
in situations when getdelays is running for a long time (i.e, the log file
growing) and you need to rotate the logs but don't want to lose any log
data.
Sample usage:
1 # ./getdelays -m0,1,2,3 -l -w getdelays.log &
(time passes)
2 # mv getdelays.log getdelays.log.1
3 # kill -USR1 <getdelays pid>
line 1: starts the program
line 2: renames the logfile. The log descriptor is still open and data
being written to the log (assuming we didn't cross mountpoints)
line 3: getdelays closes the old descriptor and reopens getdelays.log
Note on 'volatile' usage:
I know this is generally frowned on, but I think it's needed here to avoid
the compiler optimizing away the variable (it will appear as if it's never
called, since its value only changes in the signal handler).
Cc: Matt Heaton <matt@xxxxxxxxxxxx>
Cc: Balbir Singh <balbir@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/accounting/getdelays.c | 37 ++++++++++++++++++++-----
1 file changed, 31 insertions(+), 6 deletions(-)
diff -puN Documentation/accounting/getdelays.c~getdelaysc-add-a-usr1-signal-handler Documentation/accounting/getdelays.c
--- a/Documentation/accounting/getdelays.c~getdelaysc-add-a-usr1-signal-handler
+++ a/Documentation/accounting/getdelays.c
@@ -50,6 +50,7 @@ int dbg;
int print_delays;
int print_io_accounting;
int print_task_context_switch_counts;
+volatile sig_atomic_t reopen_log = 0;
__u64 stime, utime;
#define PRINTF(fmt, arg...) { \
@@ -80,6 +81,7 @@ static void usage(void)
fprintf(stderr, " -l: listen forever\n");
fprintf(stderr, " -v: debug on\n");
fprintf(stderr, " -C: container path\n");
+ fprintf(stderr, "\nSend USR1 to reopen the logfile if -w is used.\n");
}
/*
@@ -231,6 +233,30 @@ void print_ioacct(struct taskstats *t)
(unsigned long long)t->cancelled_write_bytes);
}
+void catch_usr1(int sig)
+{
+ reopen_log = 1;
+ signal(sig, catch_usr1);
+}
+
+int reopen_logfile(int fd, char *logfile)
+{
+ if (fd) {
+ PRINTF("USR1 received. Closing logfile.\n");
+ close(fd);
+ }
+ fd = open(logfile, O_WRONLY | O_CREAT | O_TRUNC,
+ S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
+ if (fd == -1) {
+ perror("Cannot open output file\n");
+ exit(1);
+ }
+
+ reopen_log = 0;
+
+ return fd;
+}
+
int main(int argc, char *argv[])
{
int c, rc, rep_len, aggr_len, len2, cmd_type;
@@ -320,12 +346,8 @@ int main(int argc, char *argv[])
}
if (write_file) {
- fd = open(logfile, O_WRONLY | O_CREAT | O_TRUNC,
- S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
- if (fd == -1) {
- perror("Cannot open output file\n");
- exit(1);
- }
+ fd = reopen_logfile(fd, logfile);
+ signal(SIGUSR1, catch_usr1); /* only set when write_file is set */
}
if ((nl_sd = create_nl_socket(NETLINK_GENERIC)) < 0)
@@ -444,6 +466,9 @@ int main(int argc, char *argv[])
err(1,"write error\n");
}
}
+ if (reopen_log) {
+ fd = reopen_logfile(fd, logfile);
+ }
if (!loop)
goto done;
break;
_
Patches currently in -mm which might be from scott@xxxxxxxxxxxx are
getdelaysc-add-a-usr1-signal-handler.patch
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