[ltt-dev] [UST PATCH] Remove all "usterr.h" references in libusctl/ustcomm
Nils Carlson
nils.carlson at ludd.ltu.se
Fri Apr 1 16:57:51 EDT 2011
On Apr 1, 2011, at 10:51 PM, Mathieu Desnoyers wrote:
> * Nils Carlson (nils.carlson at ludd.ltu.se) wrote:
>>
>> On Apr 1, 2011, at 10:24 PM, Mathieu Desnoyers wrote:
>>
>>> * Nils Carlson (nils.carlson at ludd.ltu.se) wrote:
>>>>
>>>> On Apr 1, 2011, at 5:14 PM, Mathieu Desnoyers wrote:
>>>>
>>>>> * Nils Carlson (nils.carlson at ericsson.com) wrote:
>>>>>> This patch removes all references to usterr.h and functions in
>>>>>> usterr.h from libustctl and ustcomm. This is done for three
>>>>>> reasons:
>>>>>>
>>>>>> 1. DBG, ERR, PERROR etc call in ust_safe_snprintf, I don't know
>>>>>> why, and I can't figure out any good reasons. If somebody
>>>>>> can enlighten me I would be very grateful. The only thing
>>>>>> I can figure out is that these are some sort of "signal safe"
>>>>>> printf.
>>>>>
>>>>> Yep, that's right.
>>>>>
>>>>>>
>>>>>> 2. All this stuff is quite stable and working and libraries
>>>>>> really
>>>>>> shouldn't be printing stuff.
>>>>>
>>>>> What I disagree about the patch below is that you are removing
>>>>> debug
>>>>> error printouts without taking care of some of the error values in
>>>>> many
>>>>> cases (just ignoring them).
>>>>>
>>>>> So we start from a dubtious behavior (debug error messages was not
>>>>> the
>>>>> proper way to handle error values; they should rather have been
>>>>> treated
>>>>> and pushed to the callers), to just ignoring the errors, which is
>>>>> kind
>>>>> of bad, you know... ;)
>>>>>
>>>>> So I would expect that all the error values you remove debug
>>>>> messages
>>>>> from should be dealt with rather than ignored.
>>>>
>>>> Hm. errno's are still there... As long as errnos aren't overwritten
>>>> they
>>>> can still be used. Can't find anywhere where we are making calls
>>>> that
>>>> should overwrite errnos. We could try to introduce consistency in
>>>> returning negative errno's though. That would be a separate patch.
>>>>>
>>>>>>
>>>>>> 3. This allows me to compile lttng-tools without linking
>>>>>> libustctl
>>>>>> to the ust_snprintf family of functions. This makes me happy.
>>>>>
>>>>> Well, you could just create a set of debug macros that use the
>>>>> standard
>>>>> printf, and decide at compile-time if the log output is built or
>>>>> not
>>>>> with these pretty simple macros. This change would make more sense
>>>>> to
>>>>> me
>>>>> than removing the debugging code we have there.
>>>>>
>>>> Well, could do that... but as noted, this is pretty stable stuff
>>>> and
>>>> we
>>>> can add debug code as needed I think.
>>>>
>>>>> More comments below,
>>>>>
>>>>>>
>>>>>> Mathieu, enlighten me as best you can... :-)
>>>>>>
>>>>>> Signed-off-by: Nils Carlson <nils.carlson at ericsson.com>
>>>>>> ---
>>>>>> libustcomm/ustcomm.c | 52 ++++
>>>>>> +-------------------------------------------
>>>>>> libustctl/libustctl.c | 13 ++---------
>>>>>> 2 files changed, 9 insertions(+), 56 deletions(-)
>>>>>>
>>>>>> diff --git a/libustcomm/ustcomm.c b/libustcomm/ustcomm.c
>>>>>> index dcf8cd8..2a5acc7 100644
>>>>>> --- a/libustcomm/ustcomm.c
>>>>>> +++ b/libustcomm/ustcomm.c
>>>>>> @@ -29,13 +29,14 @@
>>>>>> #include <sys/epoll.h>
>>>>>> #include <sys/stat.h>
>>>>>>
>>>>>> +#include <stdarg.h>
>>>>>> #include <stdio.h>
>>>>>> #include <stdlib.h>
>>>>>> #include <string.h>
>>>>>> #include <execinfo.h>
>>>>>>
>>>>>> #include "ustcomm.h"
>>>>>> -#include "usterr.h"
>>>>>> +#include <ust/core.h>
>>>>>> #include "share.h"
>>>>>>
>>>>>> static int mkdir_p(const char *path, mode_t mode)
>>>>>> @@ -101,7 +102,6 @@ static struct sockaddr_un *
>>>>>> create_sock_addr(const char *name,
>>>>>>
>>>>>> addr = malloc(alloc_size);
>>>>>> if (addr < 0) {
>>>>>
>>>>> Hrm, the original test is bogus there ? malloc returns NULL if
>>>>> alloc
>>>>> fails, not a negative value... ?
>>>>
>>>> True... Could fix that in a seperate patch.
>>>>>
>>>>>> - ERR("allocating addr failed");
>>>>>> return NULL;
>>>>>> }
>>>>>>
>>>>>> @@ -149,9 +149,7 @@ void ustcomm_del_sock(struct ustcomm_sock
>>>>>> *sock,
>>>>>> int keep_in_epoll)
>>>>>> {
>>>>>> cds_list_del(&sock->list);
>>>>>> if (!keep_in_epoll) {
>>>>>> - if (epoll_ctl(sock->epoll_fd, EPOLL_CTL_DEL, sock->fd, NULL)
>>>>>> ==
>>>>>> -1) {
>>>>>> - PERROR("epoll_ctl: failed to delete socket");
>>>>>> - }
>>>>>> + epoll_ctl(sock->epoll_fd, EPOLL_CTL_DEL, sock->fd, NULL);
>>>>>
>>>>> I think we should keep the error value test here ?
>>>>
>>>> No, EPOLL_CTL_DEL can only return error ENONENT, if there was no fd
>>>> with
>>>> that fd number, in which cas everything anyway is fine.
>>>
>>> This is the kind of obvious safety net we should leave in place.
>>> It's
>>> not because we expect that we'll always pass a valid FD that we
>>> won't
>>> have a bug creeping in at some point, and checking the returned
>>> error
>>> value is the kind of safety measure that will help us diagnose
>>> problems
>>> much more quickly in the long run.
>> hm. Remember, this is a tracing library. It should be quiet.
>>
>> What do you suggest we do with the error? the function doesn't return
>> anything.
>> The only thing we can do is spew out a error message, which if we are
>> lucky may be reported, probably be ignored, and in worst case screw
>> up a
>> program using stdout/stderr for something.
>>
>> Maybe we should discuss this though. What should UST do/not-do.
>> Should
>> UST ever throw stuff out on stdout/stderr?
>
> Aren't these text error messages already channeled through separate
> file
> descriptors through UST-specific log files which are saved along the
> recorded traces ?
>
Nope, go straight to stderr. We could discuss logfiles though, but
then they should be configured by an environment variable, ie. not on
by default.
>>
>>>
>>>>
>>>>>
>>>>>> }
>>>>>> close(sock->fd);
>>>>>> free(sock);
>>>>>> @@ -168,13 +166,11 @@ struct ustcomm_sock *
>>>>>> ustcomm_init_named_socket(const char *name,
>>>>>>
>>>>>> fd = socket(PF_UNIX, SOCK_STREAM, 0);
>>>>>> if(fd == -1) {
>>>>>> - PERROR("socket");
>>>>>> return NULL;
>>>>>> }
>>>>>>
>>>>>> addr = create_sock_addr(name, &sock_addr_size);
>>>>>> if (addr == NULL) {
>>>>>> - ERR("allocating addr, UST thread bailing");
>>>>>> goto close_sock;
>>>>>> }
>>>>>>
>>>>>> @@ -182,29 +178,24 @@ struct ustcomm_sock *
>>>>>> ustcomm_init_named_socket(const char *name,
>>>>>> if(result == 0) {
>>>>>> /* file exists */
>>>>>> result = unlink(name);
>>>>>> - if(result == -1) {
>>>>>> - PERROR("unlink of socket file");
>>>>>> + if (result == -1) {
>>>>>> goto free_addr;
>>>>>> }
>>>>>> - DBG("socket already exists; overwriting");
>>>>>> }
>>>>>>
>>>>>> result = bind(fd, (struct sockaddr *)addr, sock_addr_size);
>>>>>> if(result == -1) {
>>>>>> - PERROR("bind");
>>>>>> goto free_addr;
>>>>>> }
>>>>>>
>>>>>> result = listen(fd, 1);
>>>>>> if(result == -1) {
>>>>>> - PERROR("listen");
>>>>>> goto free_addr;
>>>>>> }
>>>>>>
>>>>>> sock = ustcomm_init_sock(fd, epoll_fd,
>>>>>> NULL);
>>>>>> if (!sock) {
>>>>>> - ERR("failed to create ustcomm_sock");
>>>>>> goto free_addr;
>>>>>> }
>>>>>>
>>>>>> @@ -236,39 +227,31 @@ void ustcomm_del_named_sock(struct
>>>>>> ustcomm_sock *sock,
>>>>>> /* Get the socket name */
>>>>>> alloc_size = sizeof(dummy);
>>>>>> if (getsockname(fd, &dummy, (socklen_t *)&alloc_size) < 0) {
>>>>>> - PERROR("getsockname failed");
>>>>>> goto del_sock;
>>>>>> }
>>>>>>
>>>>>> sockaddr = zmalloc(alloc_size);
>>>>>> if (!sockaddr) {
>>>>>> - ERR("failed to allocate sockaddr");
>>>>>> goto del_sock;
>>>>>> }
>>>>>>
>>>>>> if (getsockname(fd, sockaddr, (socklen_t *)&alloc_size) < 0) {
>>>>>> - PERROR("getsockname failed");
>>>>>> goto free_sockaddr;
>>>>>> }
>>>>>>
>>>>>> /* Destroy socket */
>>>>>> result = stat(sockaddr->sun_path, &st);
>>>>>> if(result < 0) {
>>>>>> - PERROR("stat (%s)", sockaddr->sun_path);
>>>>>> goto free_sockaddr;
>>>>>> }
>>>>>>
>>>>>> /* Paranoid check before deleting. */
>>>>>> result = S_ISSOCK(st.st_mode);
>>>>>> if(!result) {
>>>>>> - ERR("The socket we are about to delete is not a socket.");
>>>>>> goto free_sockaddr;
>>>>>> }
>>>>>>
>>>>>> - result = unlink(sockaddr->sun_path);
>>>>>> - if(result < 0) {
>>>>>> - PERROR("unlink");
>>>>>> - }
>>>>>> + unlink(sockaddr->sun_path);
>>>>>
>>>>> Should we do something with the error here ? Why is it not treated
>>>>> (if
>>>>> there is a reason, we should add a comment)
>>>>
>>>> hm, could add a comment but not much point. This is just cleanup
>>>> after
>>>> all, if it fails we can't do anything about it and it won't affect
>>>> anything.
>>>
>>> I recommend this to ensure that all return values are either
>>>
>>> - treated, or
>>> - documented.
>>>
>>> looking at unlink(2), there are many reasons why unlink can fail. If
>>> it
>>> fails due to incorrect access rights (for instance), we probably
>>> want
>>> to
>>> propagate the error up to the user, no ?
>>
>> For what? Nothing the user can/should do anyway.
>
> Reporting when the developer/distribution screw things up, mostly. :)
> I've got used to expect all the unexpected ways things can go wrong
> with
> projects deployed in a wide range of environments by yet unknown
> people.
>
> Reporting errors should not be about reporting expected error cases,
> but
> covering all the paths.
>
Sounds good in theory, but again, what do we want to send out? this is
a void function.
But the logfile turned on by an environment variable may not be a bad
idea. This way users could turn it on to check for strange behaviour.
Why do we want the signal safe printf by the way? When are we using
this stuff in signal handlers?
/Nils
> Thanks,
>
> Mathieu
>
>>
>> /Nils
>>>
>>> Thanks,
>>>
>>> Mathieu
>>>
>>>>
>>>> /Nils
>>>>
>>>>>
>>>>> Thanks,
>>>>>
>>>>> Mathieu
>>>>>
>>>>>> }
>>>>>>
>>>>>> free_sockaddr:
>>>>>> @@ -297,7 +280,6 @@ int ustcomm_recv_alloc(int sock,
>>>>>> } else if (errno == EINTR) {
>>>>>> return -1;
>>>>>> } else if (result < 0) {
>>>>>> - PERROR("recv");
>>>>>> return -1;
>>>>>> }
>>>>>> return 0;
>>>>>> @@ -326,7 +308,6 @@ int ustcomm_recv_alloc(int sock,
>>>>>> result = recvmsg(sock, &msg, MSG_WAITALL);
>>>>>> if (result < 0) {
>>>>>> free(*data);
>>>>>> - PERROR("recvmsg failed");
>>>>>> }
>>>>>>
>>>>>> return result;
>>>>>> @@ -355,7 +336,6 @@ int ustcomm_recv_fd(int sock,
>>>>>> } else if (errno == EINTR) {
>>>>>> return -1;
>>>>>> } else if (result < 0) {
>>>>>> - PERROR("recv");
>>>>>> return -1;
>>>>>> }
>>>>>> return 0;
>>>>>> @@ -372,7 +352,6 @@ int ustcomm_recv_fd(int sock,
>>>>>> if (peek_header.size && data) {
>>>>>> if (peek_header.size < 0 ||
>>>>>> peek_header.size > USTCOMM_DATA_SIZE) {
>>>>>> - ERR("big peek header! %ld", peek_header.size);
>>>>>> return 0;
>>>>>> }
>>>>>>
>>>>>> @@ -389,9 +368,6 @@ int ustcomm_recv_fd(int sock,
>>>>>>
>>>>>> result = recvmsg(sock, &msg, MSG_WAITALL);
>>>>>> if (result <= 0) {
>>>>>> - if (result < 0) {
>>>>>> - PERROR("recvmsg failed");
>>>>>> - }
>>>>>> return result;
>>>>>> }
>>>>>>
>>>>>> @@ -407,9 +383,6 @@ int ustcomm_recv_fd(int sock,
>>>>>> }
>>>>>> cmsg = CMSG_NXTHDR(&msg, cmsg);
>>>>>> }
>>>>>> - if (!result) {
>>>>>> - ERR("Failed to receive file descriptor\n");
>>>>>> - }
>>>>>> }
>>>>>>
>>>>>> return 1;
>>>>>> @@ -430,7 +403,6 @@ int ustcomm_send_fd(int sock,
>>>>>> {
>>>>>> struct iovec iov[2];
>>>>>> struct msghdr msg;
>>>>>> - int result;
>>>>>> struct cmsghdr *cmsg;
>>>>>> char buf[CMSG_SPACE(sizeof(int))];
>>>>>>
>>>>>> @@ -461,11 +433,7 @@ int ustcomm_send_fd(int sock,
>>>>>> msg.msg_controllen = cmsg->cmsg_len;
>>>>>> }
>>>>>>
>>>>>> - result = sendmsg(sock, &msg, MSG_NOSIGNAL);
>>>>>> - if (result < 0 && errno != EPIPE) {
>>>>>> - PERROR("sendmsg failed");
>>>>>> - }
>>>>>> - return result;
>>>>>> + return sendmsg(sock, &msg, MSG_NOSIGNAL);
>>>>>> }
>>>>>>
>>>>>> int ustcomm_send(int sock,
>>>>>> @@ -504,19 +472,16 @@ int ustcomm_connect_path(const char *name,
>>>>>> int
>>>>>> *connection_fd)
>>>>>>
>>>>>> fd = socket(PF_UNIX, SOCK_STREAM, 0);
>>>>>> if(fd == -1) {
>>>>>> - PERROR("socket");
>>>>>> return -1;
>>>>>> }
>>>>>>
>>>>>> addr = create_sock_addr(name, &sock_addr_size);
>>>>>> if (addr == NULL) {
>>>>>> - ERR("allocating addr failed");
>>>>>> goto close_sock;
>>>>>> }
>>>>>>
>>>>>> result = connect(fd, (struct sockaddr *)addr, sock_addr_size);
>>>>>> if(result == -1) {
>>>>>> - PERROR("connect (path=%s)", name);
>>>>>> goto free_sock_addr;
>>>>>> }
>>>>>>
>>>>>> @@ -543,7 +508,6 @@ char *ustcomm_user_sock_dir(void)
>>>>>> result = asprintf(&sock_dir, "%s%s", USER_SOCK_DIR,
>>>>>> cuserid(NULL));
>>>>>> if (result < 0) {
>>>>>> - ERR("string overflow allocating directory name");
>>>>>> return NULL;
>>>>>> }
>>>>>>
>>>>>> @@ -569,14 +533,12 @@ static int connect_app_non_root(pid_t pid,
>>>>>> int
>>>>>> *app_fd)
>>>>>>
>>>>>> result = asprintf(&sock_name, "%s/%d", dir_name, pid);
>>>>>> if (result < 0) {
>>>>>> - ERR("failed to allocate socket name");
>>>>>> retval = -1;
>>>>>> goto free_dir_name;
>>>>>> }
>>>>>>
>>>>>> result = ustcomm_connect_path(sock_name, app_fd);
>>>>>> if (result < 0) {
>>>>>> - ERR("failed to connect to app");
>>>>>> retval = -1;
>>>>>> goto free_sock_name;
>>>>>> }
>>>>>> @@ -657,14 +619,12 @@ int ensure_dir_exists(const char *dir,
>>>>>> mode_t
>>>>>> mode)
>>>>>>
>>>>>> result = mkdir_p(dir, mode);
>>>>>> if(result != 0) {
>>>>>> - ERR("executing in recursive creation of directory %s", dir);
>>>>>> return -1;
>>>>>> }
>>>>>> } else {
>>>>>> if (st.st_mode != mode) {
>>>>>> result = chmod(dir, mode);
>>>>>> if (result < 0) {
>>>>>> - ERR("couldn't set directory mode on %s", dir);
>>>>>> return -1;
>>>>>> }
>>>>>> }
>>>>>> diff --git a/libustctl/libustctl.c b/libustctl/libustctl.c
>>>>>> index 1911434..b5d6a02 100644
>>>>>> --- a/libustctl/libustctl.c
>>>>>> +++ b/libustctl/libustctl.c
>>>>>> @@ -17,6 +17,7 @@
>>>>>> */
>>>>>>
>>>>>> #define _GNU_SOURCE
>>>>>> +#include <errno.h>
>>>>>> #include <stdio.h>
>>>>>> #include <unistd.h>
>>>>>> #include <getopt.h>
>>>>>> @@ -26,8 +27,8 @@
>>>>>> #include <dirent.h>
>>>>>>
>>>>>> #include "ustcomm.h"
>>>>>> -#include "ust/ustctl.h"
>>>>>> -#include "usterr.h"
>>>>>> +#include <ust/ustctl.h>
>>>>>> +#include <ust/core.h>
>>>>>>
>>>>>> static int do_cmd(int sock,
>>>>>> const struct ustcomm_header *req_header,
>>>>>> @@ -57,7 +58,6 @@ static int do_cmd(int sock,
>>>>>> }
>>>>>> }
>>>>>> } else {
>>>>>> - ERR("ustcomm req failed");
>>>>>> if (result == 0) {
>>>>>> saved_errno = ENOTCONN;
>>>>>> } else {
>>>>>> @@ -80,7 +80,6 @@ int ustctl_connect_pid(pid_t pid)
>>>>>> int sock;
>>>>>>
>>>>>> if (ustcomm_connect_app(pid, &sock)) {
>>>>>> - ERR("could not connect to PID %u", (unsigned int) pid);
>>>>>> errno = ENOTCONN;
>>>>>> return -1;
>>>>>> }
>>>>>> @@ -580,20 +579,17 @@ int ustctl_get_cmsf(int sock, struct
>>>>>> marker_status **cmsf)
>>>>>>
>>>>>> result = ustcomm_send(sock, &req_header, NULL);
>>>>>> if (result <= 0) {
>>>>>> - PERROR("error while requesting markers list");
>>>>>> return -1;
>>>>>> }
>>>>>>
>>>>>> result = ustcomm_recv_alloc(sock, &res_header, &big_str);
>>>>>> if (result <= 0) {
>>>>>> - ERR("error while receiving markers list");
>>>>>> return -1;
>>>>>> }
>>>>>>
>>>>>> tmp_cmsf = (struct marker_status *) zmalloc(sizeof(struct
>>>>>> marker_status) *
>>>>>> (ustctl_count_nl(big_str) + 1));
>>>>>> if (tmp_cmsf == NULL) {
>>>>>> - ERR("Failed to allocate CMSF array");
>>>>>> return -1;
>>>>>> }
>>>>>>
>>>>>> @@ -672,13 +668,11 @@ int ustctl_get_tes(int sock, struct
>>>>>> trace_event_status **tes)
>>>>>>
>>>>>> result = ustcomm_send(sock, &req_header, NULL);
>>>>>> if (result != 1) {
>>>>>> - ERR("error while requesting trace_event list");
>>>>>> return -1;
>>>>>> }
>>>>>>
>>>>>> result = ustcomm_recv_alloc(sock, &res_header, &big_str);
>>>>>> if (result != 1) {
>>>>>> - ERR("error while receiving markers list");
>>>>>> return -1;
>>>>>> }
>>>>>>
>>>>>> @@ -686,7 +680,6 @@ int ustctl_get_tes(int sock, struct
>>>>>> trace_event_status **tes)
>>>>>> zmalloc(sizeof(struct trace_event_status) *
>>>>>> (ustctl_count_nl(big_str) + 1));
>>>>>> if (tmp_tes == NULL) {
>>>>>> - ERR("Failed to allocate TES array");
>>>>>> return -1;
>>>>>> }
>>>>>>
>>>>>> --
>>>>>> 1.7.1
>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>> ltt-dev mailing list
>>>>>> ltt-dev at lists.casi.polymtl.ca
>>>>>> http://lists.casi.polymtl.ca/cgi-bin/mailman/listinfo/ltt-dev
>>>>>>
>>>>>
>>>>> --
>>>>> Mathieu Desnoyers
>>>>> Operating System Efficiency R&D Consultant
>>>>> EfficiOS Inc.
>>>>> http://www.efficios.com
>>>>>
>>>>> _______________________________________________
>>>>> ltt-dev mailing list
>>>>> ltt-dev at lists.casi.polymtl.ca
>>>>> http://lists.casi.polymtl.ca/cgi-bin/mailman/listinfo/ltt-dev
>>>>
>>>
>>> --
>>> Mathieu Desnoyers
>>> Operating System Efficiency R&D Consultant
>>> EfficiOS Inc.
>>> http://www.efficios.com
>>
>
> --
> Mathieu Desnoyers
> Operating System Efficiency R&D Consultant
> EfficiOS Inc.
> http://www.efficios.com
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