systemd-bootchart: Prevent closing random file descriptors
If the kernel has no CONFIG_SCHED_DEBUG option set, systemd-bootchart produces
empty .svg file. The reason for this is very fragile file descriptor logic in
log_sample() and main() (/* do some cleanup, close fd's */ block). There are
many places where file descriptors are closed on failure (missing SCHED_DEBUG
provokes it), but there are several problems with it:
- following iterations in the loop see that the descriptor is non zero and do
not open the corresponding file again;
- "some cleanup" code closes already closed files and the descriptors are reused
already, in particular for resulting .svg file;
- static "vmstat" and "schedstat" variables in log_sample() made the situation
even worse.
These are the strace fragments:
[...]
close(7) = -1 EBADF (Bad file descriptor)
close(-1) = -1 EBADF (Bad file descriptor)
pread(7, 0xbea60a2c, 4095, 0) = -1 EBADF (Bad file descriptor)
close(7) = -1 EBADF (Bad file descriptor)
close(-1) = -1 EBADF (Bad file descriptor)
pread(7, 0xbea60a2c, 4095, 0) = -1 EBADF (Bad file descriptor)
close(7) = -1 EBADF (Bad file descriptor)
close(-1) = -1 EBADF (Bad file descriptor)
getdents64(4, /* 0 entries */, 32768) = 0
clock_gettime(CLOCK_MONOTONIC, {24, 783843501}) = 0
nanosleep({0, 5221792}, NULL) = 0
clock_gettime(CLOCK_MONOTONIC, {24, 789726835}) = 0
lseek(4, 0, SEEK_SET) = 0
pread(5, "nr_free_pages 52309\nnr_alloc_bat"..., 4095, 0) = 685
pread(6, "version 15\ntimestamp 4294939775\n"..., 4095, 0) = 86
getdents64(4, /* 99 entries */, 32768) = 2680
pread(7, 0xbea60a2c, 4095, 0) = -1 EBADF (Bad file descriptor)
close(7) = -1 EBADF (Bad file descriptor)
close(-1) = -1 EBADF (Bad file descriptor)
pread(8, 0xbea60a2c, 4095, 0) = -1 EBADF (Bad file descriptor)
close(8) = -1 EBADF (Bad file descriptor)
close(-1) = -1 EBADF (Bad file descriptor)
pread(9, 0xbea60a2c, 4095, 0) = -1 EBADF (Bad file descriptor)
close(9) = -1 EBADF (Bad file descriptor)
[...]
where it obviously tries to close same and reused decriptors many times, also
passing return code "-1" instead of descriptor...
[...]
close(7) = -1 EBADF (Bad file descriptor)
close(-1) = -1 EBADF (Bad file descriptor)
pipe2([7, 8], O_CLOEXEC) = 0
clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0xb6fd0068) = 192
close(8) = 0
fcntl64(7, F_SETFD, 0) = 0
fstat64(7, {st_mode=S_IFIFO|0600, st_size=0, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb6fd2000
read(7, "[ 0.074507] calling vfp_init"..., 4096) = 4096
[...]
read(7, "s)\n[ 6.228910] UBIFS: reserve"..., 4096) = 4096
read(7, "trary Executable File Formats Fi"..., 4096) = 1616
read(7, "", 4096) = 0
close(7) = 0
wait4(192, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], 0, NULL) = 192
This commit is contained in:
Alexander Sverdlin
committed by
Daniel Mack
Daniel Mack
parent
333e07b793
commit
9964a9eb7b
@@ -448,9 +448,9 @@ int main(int argc, char *argv[]) {
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ps = ps_first;
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while (ps->next_ps) {
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ps = ps->next_ps;
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if (ps->schedstat)
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if (ps->schedstat >= 0)
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close(ps->schedstat);
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if (ps->sched)
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if (ps->sched >= 0)
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close(ps->sched);
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if (ps->smaps)
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fclose(ps->smaps);
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+19
-8
@@ -108,8 +108,8 @@ static int pid_cmdline_strscpy(char *buffer, size_t buf_len, int pid) {
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}
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void log_sample(int sample, struct list_sample_data **ptr) {
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static int vmstat;
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static int schedstat;
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static int vmstat = -1;
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static int schedstat = -1;
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char buf[4096];
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char key[256];
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char val[256];
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@@ -140,7 +140,7 @@ void log_sample(int sample, struct list_sample_data **ptr) {
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rewinddir(proc);
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}
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if (!vmstat) {
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if (vmstat < 0) {
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/* block stuff */
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vmstat = openat(procfd, "vmstat", O_RDONLY);
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if (vmstat == -1) {
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@@ -152,6 +152,7 @@ void log_sample(int sample, struct list_sample_data **ptr) {
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n = pread(vmstat, buf, sizeof(buf) - 1, 0);
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if (n <= 0) {
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close(vmstat);
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vmstat = -1;
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return;
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}
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buf[n] = '\0';
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@@ -172,7 +173,7 @@ vmstat_next:
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break;
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}
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if (!schedstat) {
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if (schedstat < 0) {
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/* overall CPU utilization */
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schedstat = openat(procfd, "schedstat", O_RDONLY);
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if (schedstat == -1) {
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@@ -184,6 +185,7 @@ vmstat_next:
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n = pread(schedstat, buf, sizeof(buf) - 1, 0);
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if (n <= 0) {
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close(schedstat);
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schedstat = -1;
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return;
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}
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buf[n] = '\0';
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@@ -260,6 +262,8 @@ schedstat_next:
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}
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ps = ps->next_ps;
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ps->pid = pid;
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ps->sched = -1;
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ps->schedstat = -1;
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ps->sample = new0(struct ps_sched_struct, 1);
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if (!ps->sample) {
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@@ -276,7 +280,7 @@ schedstat_next:
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ps->sample->waittime = atoll(wt);
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/* get name, start time */
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if (!ps->sched) {
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if (ps->sched < 0) {
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sprintf(filename, "%d/sched", pid);
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ps->sched = openat(procfd, filename, O_RDONLY);
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if (ps->sched == -1)
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@@ -286,6 +290,7 @@ schedstat_next:
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s = pread(ps->sched, buf, sizeof(buf) - 1, 0);
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if (s <= 0) {
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close(ps->sched);
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ps->sched = -1;
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continue;
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}
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buf[s] = '\0';
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@@ -377,7 +382,7 @@ schedstat_next:
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* iteration */
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/* rt, wt */
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if (!ps->schedstat) {
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if (ps->schedstat < 0) {
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sprintf(filename, "%d/schedstat", pid);
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ps->schedstat = openat(procfd, filename, O_RDONLY);
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if (ps->schedstat == -1)
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@@ -387,8 +392,11 @@ schedstat_next:
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if (s <= 0) {
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/* clean up our file descriptors - assume that the process exited */
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close(ps->schedstat);
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if (ps->sched)
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ps->schedstat = -1;
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if (ps->sched) {
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close(ps->sched);
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ps->sched = -1;
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}
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//if (ps->smaps)
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// fclose(ps->smaps);
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continue;
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@@ -488,8 +496,11 @@ catch_rename:
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if (s <= 0) {
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/* clean up file descriptors */
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close(ps->sched);
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if (ps->schedstat)
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ps->sched = -1;
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if (ps->schedstat) {
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close(ps->schedstat);
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ps->schedstat = -1;
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}
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//if (ps->smaps)
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// fclose(ps->smaps);
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continue;
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