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author | Alexander Sverdlin <alexander.sverdlin@gmail.com> | 2015-03-29 20:41:56 +0200 |
---|---|---|
committer | Daniel Mack <daniel@zonque.org> | 2015-03-30 01:08:05 +0200 |
commit | 9964a9eb7b18d6ad172a7921cf88efabde05d121 (patch) | |
tree | 063667d969bef12bf77bd21f7690365531b771f1 /src/bootchart/store.c | |
parent | 333e07b793836442dc320c60d5ae66f95c4489e1 (diff) | |
download | systemd-9964a9eb7b18d6ad172a7921cf88efabde05d121.tar.gz |
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
Diffstat (limited to 'src/bootchart/store.c')
-rw-r--r-- | src/bootchart/store.c | 27 |
1 files changed, 19 insertions, 8 deletions
diff --git a/src/bootchart/store.c b/src/bootchart/store.c index dfa681f223..3900936acf 100644 --- a/src/bootchart/store.c +++ b/src/bootchart/store.c @@ -108,8 +108,8 @@ static int pid_cmdline_strscpy(char *buffer, size_t buf_len, int pid) { } void log_sample(int sample, struct list_sample_data **ptr) { - static int vmstat; - static int schedstat; + static int vmstat = -1; + static int schedstat = -1; char buf[4096]; char key[256]; char val[256]; @@ -140,7 +140,7 @@ void log_sample(int sample, struct list_sample_data **ptr) { rewinddir(proc); } - if (!vmstat) { + if (vmstat < 0) { /* block stuff */ vmstat = openat(procfd, "vmstat", O_RDONLY); if (vmstat == -1) { @@ -152,6 +152,7 @@ void log_sample(int sample, struct list_sample_data **ptr) { n = pread(vmstat, buf, sizeof(buf) - 1, 0); if (n <= 0) { close(vmstat); + vmstat = -1; return; } buf[n] = '\0'; @@ -172,7 +173,7 @@ vmstat_next: break; } - if (!schedstat) { + if (schedstat < 0) { /* overall CPU utilization */ schedstat = openat(procfd, "schedstat", O_RDONLY); if (schedstat == -1) { @@ -184,6 +185,7 @@ vmstat_next: n = pread(schedstat, buf, sizeof(buf) - 1, 0); if (n <= 0) { close(schedstat); + schedstat = -1; return; } buf[n] = '\0'; @@ -260,6 +262,8 @@ schedstat_next: } ps = ps->next_ps; ps->pid = pid; + ps->sched = -1; + ps->schedstat = -1; ps->sample = new0(struct ps_sched_struct, 1); if (!ps->sample) { @@ -276,7 +280,7 @@ schedstat_next: ps->sample->waittime = atoll(wt); /* get name, start time */ - if (!ps->sched) { + if (ps->sched < 0) { sprintf(filename, "%d/sched", pid); ps->sched = openat(procfd, filename, O_RDONLY); if (ps->sched == -1) @@ -286,6 +290,7 @@ schedstat_next: s = pread(ps->sched, buf, sizeof(buf) - 1, 0); if (s <= 0) { close(ps->sched); + ps->sched = -1; continue; } buf[s] = '\0'; @@ -377,7 +382,7 @@ schedstat_next: * iteration */ /* rt, wt */ - if (!ps->schedstat) { + if (ps->schedstat < 0) { sprintf(filename, "%d/schedstat", pid); ps->schedstat = openat(procfd, filename, O_RDONLY); if (ps->schedstat == -1) @@ -387,8 +392,11 @@ schedstat_next: if (s <= 0) { /* clean up our file descriptors - assume that the process exited */ close(ps->schedstat); - if (ps->sched) + ps->schedstat = -1; + if (ps->sched) { close(ps->sched); + ps->sched = -1; + } //if (ps->smaps) // fclose(ps->smaps); continue; @@ -488,8 +496,11 @@ catch_rename: if (s <= 0) { /* clean up file descriptors */ close(ps->sched); - if (ps->schedstat) + ps->sched = -1; + if (ps->schedstat) { close(ps->schedstat); + ps->schedstat = -1; + } //if (ps->smaps) // fclose(ps->smaps); continue; |