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journald: don't employ inner loop for reading from incoming sockets

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Otherwise, if the socket is constantly busy we will never return to the
event loop, but we really need to to dispatch other (possibly more
high-priority) events too. Hence, return after dispatching one message
to the event handler, and rely on the event loop calling us back
right-away.

Fixes #125
This commit is contained in:
Lennart Poettering
2015-06-10 20:09:10 +02:00
parent a8467435a0
commit a315ac4e07
1 changed files with 103 additions and 107 deletions
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src/journal/journald-server.c
+103 -107
View File
@@ -1104,6 +1104,42 @@ finish:
int server_process_datagram(sd_event_source *es, int fd, uint32_t revents, void *userdata) {
Server *s = userdata;
struct ucred *ucred = NULL;
struct timeval *tv = NULL;
struct cmsghdr *cmsg;
char *label = NULL;
size_t label_len = 0, m;
struct iovec iovec;
ssize_t n;
int *fds = NULL, v = 0;
unsigned n_fds = 0;
union {
struct cmsghdr cmsghdr;
/* We use NAME_MAX space for the SELinux label
* here. The kernel currently enforces no
* limit, but according to suggestions from
* the SELinux people this will change and it
* will probably be identical to NAME_MAX. For
* now we use that, but this should be updated
* one day when the final limit is known. */
uint8_t buf[CMSG_SPACE(sizeof(struct ucred)) +
CMSG_SPACE(sizeof(struct timeval)) +
CMSG_SPACE(sizeof(int)) + /* fd */
CMSG_SPACE(NAME_MAX)]; /* selinux label */
} control = {};
union sockaddr_union sa = {};
struct msghdr msghdr = {
.msg_iov = &iovec,
.msg_iovlen = 1,
.msg_control = &control,
.msg_controllen = sizeof(control),
.msg_name = &sa,
.msg_namelen = sizeof(sa),
};
assert(s);
assert(fd == s->native_fd || fd == s->syslog_fd || fd == s->audit_fd);
@@ -1113,119 +1149,79 @@ int server_process_datagram(sd_event_source *es, int fd, uint32_t revents, void
return -EIO;
}
for (;;) {
struct ucred *ucred = NULL;
struct timeval *tv = NULL;
struct cmsghdr *cmsg;
char *label = NULL;
size_t label_len = 0;
struct iovec iovec;
/* Try to get the right size, if we can. (Not all
* sockets support SIOCINQ, hence we just try, but
* don't rely on it. */
(void) ioctl(fd, SIOCINQ, &v);
union {
struct cmsghdr cmsghdr;
/* Fix it up, if it is too small. We use the same fixed value as auditd here. Awful! */
m = PAGE_ALIGN(MAX3((size_t) v + 1,
(size_t) LINE_MAX,
ALIGN(sizeof(struct nlmsghdr)) + ALIGN((size_t) MAX_AUDIT_MESSAGE_LENGTH)) + 1);
/* We use NAME_MAX space for the SELinux label
* here. The kernel currently enforces no
* limit, but according to suggestions from
* the SELinux people this will change and it
* will probably be identical to NAME_MAX. For
* now we use that, but this should be updated
* one day when the final limit is known. */
uint8_t buf[CMSG_SPACE(sizeof(struct ucred)) +
CMSG_SPACE(sizeof(struct timeval)) +
CMSG_SPACE(sizeof(int)) + /* fd */
CMSG_SPACE(NAME_MAX)]; /* selinux label */
} control = {};
union sockaddr_union sa = {};
struct msghdr msghdr = {
.msg_iov = &iovec,
.msg_iovlen = 1,
.msg_control = &control,
.msg_controllen = sizeof(control),
.msg_name = &sa,
.msg_namelen = sizeof(sa),
};
if (!GREEDY_REALLOC(s->buffer, s->buffer_size, m))
return log_oom();
ssize_t n;
int *fds = NULL;
unsigned n_fds = 0;
int v = 0;
size_t m;
iovec.iov_base = s->buffer;
iovec.iov_len = s->buffer_size - 1; /* Leave room for trailing NUL we add later */
/* Try to get the right size, if we can. (Not all
* sockets support SIOCINQ, hence we just try, but
* don't rely on it. */
(void) ioctl(fd, SIOCINQ, &v);
n = recvmsg(fd, &msghdr, MSG_DONTWAIT|MSG_CMSG_CLOEXEC);
if (n < 0) {
if (errno == EINTR || errno == EAGAIN)
return 0;
/* Fix it up, if it is too small. We use the same fixed value as auditd here. Awful! */
m = PAGE_ALIGN(MAX3((size_t) v + 1,
(size_t) LINE_MAX,
ALIGN(sizeof(struct nlmsghdr)) + ALIGN((size_t) MAX_AUDIT_MESSAGE_LENGTH)) + 1);
if (!GREEDY_REALLOC(s->buffer, s->buffer_size, m))
return log_oom();
iovec.iov_base = s->buffer;
iovec.iov_len = s->buffer_size - 1; /* Leave room for trailing NUL we add later */
n = recvmsg(fd, &msghdr, MSG_DONTWAIT|MSG_CMSG_CLOEXEC);
if (n < 0) {
if (errno == EINTR || errno == EAGAIN)
return 0;
log_error_errno(errno, "recvmsg() failed: %m");
return -errno;
}
CMSG_FOREACH(cmsg, &msghdr) {
if (cmsg->cmsg_level == SOL_SOCKET &&
cmsg->cmsg_type == SCM_CREDENTIALS &&
cmsg->cmsg_len == CMSG_LEN(sizeof(struct ucred)))
ucred = (struct ucred*) CMSG_DATA(cmsg);
else if (cmsg->cmsg_level == SOL_SOCKET &&
cmsg->cmsg_type == SCM_SECURITY) {
label = (char*) CMSG_DATA(cmsg);
label_len = cmsg->cmsg_len - CMSG_LEN(0);
} else if (cmsg->cmsg_level == SOL_SOCKET &&
cmsg->cmsg_type == SO_TIMESTAMP &&
cmsg->cmsg_len == CMSG_LEN(sizeof(struct timeval)))
tv = (struct timeval*) CMSG_DATA(cmsg);
else if (cmsg->cmsg_level == SOL_SOCKET &&
cmsg->cmsg_type == SCM_RIGHTS) {
fds = (int*) CMSG_DATA(cmsg);
n_fds = (cmsg->cmsg_len - CMSG_LEN(0)) / sizeof(int);
}
}
/* And a trailing NUL, just in case */
s->buffer[n] = 0;
if (fd == s->syslog_fd) {
if (n > 0 && n_fds == 0)
server_process_syslog_message(s, strstrip(s->buffer), ucred, tv, label, label_len);
else if (n_fds > 0)
log_warning("Got file descriptors via syslog socket. Ignoring.");
} else if (fd == s->native_fd) {
if (n > 0 && n_fds == 0)
server_process_native_message(s, s->buffer, n, ucred, tv, label, label_len);
else if (n == 0 && n_fds == 1)
server_process_native_file(s, fds[0], ucred, tv, label, label_len);
else if (n_fds > 0)
log_warning("Got too many file descriptors via native socket. Ignoring.");
} else {
assert(fd == s->audit_fd);
if (n > 0 && n_fds == 0)
server_process_audit_message(s, s->buffer, n, ucred, &sa, msghdr.msg_namelen);
else if (n_fds > 0)
log_warning("Got file descriptors via audit socket. Ignoring.");
}
close_many(fds, n_fds);
return log_error_errno(errno, "recvmsg() failed: %m");
}
CMSG_FOREACH(cmsg, &msghdr) {
if (cmsg->cmsg_level == SOL_SOCKET &&
cmsg->cmsg_type == SCM_CREDENTIALS &&
cmsg->cmsg_len == CMSG_LEN(sizeof(struct ucred)))
ucred = (struct ucred*) CMSG_DATA(cmsg);
else if (cmsg->cmsg_level == SOL_SOCKET &&
cmsg->cmsg_type == SCM_SECURITY) {
label = (char*) CMSG_DATA(cmsg);
label_len = cmsg->cmsg_len - CMSG_LEN(0);
} else if (cmsg->cmsg_level == SOL_SOCKET &&
cmsg->cmsg_type == SO_TIMESTAMP &&
cmsg->cmsg_len == CMSG_LEN(sizeof(struct timeval)))
tv = (struct timeval*) CMSG_DATA(cmsg);
else if (cmsg->cmsg_level == SOL_SOCKET &&
cmsg->cmsg_type == SCM_RIGHTS) {
fds = (int*) CMSG_DATA(cmsg);
n_fds = (cmsg->cmsg_len - CMSG_LEN(0)) / sizeof(int);
}
}
/* And a trailing NUL, just in case */
s->buffer[n] = 0;
if (fd == s->syslog_fd) {
if (n > 0 && n_fds == 0)
server_process_syslog_message(s, strstrip(s->buffer), ucred, tv, label, label_len);
else if (n_fds > 0)
log_warning("Got file descriptors via syslog socket. Ignoring.");
} else if (fd == s->native_fd) {
if (n > 0 && n_fds == 0)
server_process_native_message(s, s->buffer, n, ucred, tv, label, label_len);
else if (n == 0 && n_fds == 1)
server_process_native_file(s, fds[0], ucred, tv, label, label_len);
else if (n_fds > 0)
log_warning("Got too many file descriptors via native socket. Ignoring.");
} else {
assert(fd == s->audit_fd);
if (n > 0 && n_fds == 0)
server_process_audit_message(s, s->buffer, n, ucred, &sa, msghdr.msg_namelen);
else if (n_fds > 0)
log_warning("Got file descriptors via audit socket. Ignoring.");
}
close_many(fds, n_fds);
return 0;
}
static int dispatch_sigusr1(sd_event_source *es, const struct signalfd_siginfo *si, void *userdata) {