<p>pespin has uploaded this change for <strong>review</strong>.</p><p><a href="https://gerrit.osmocom.org/c/libosmocore/+/26089">View Change</a></p><pre style="font-family: monospace,monospace; white-space: pre-wrap;">logging: Fix double lock of log_tgt_mutex<br><br>Recent commit introduced the "blocking-io" param to "log stderr" VTY<br>command, which calls log_target_file_switch_to_{stream,wqueue}.<br>The VTY command already locks the log_tgt_mutex mutex, since it has to<br>access the tgt list. However, the functions mention above also want to<br>lock the same mutex in order to log information. Let's drop the logging<br>to avoid the double lock, and update its documentation to mention it<br>must be called with the lock already held, as documented on other<br>similar functions.<br><br>Fixes: b72867f0e68c96ca25e1f9929ce92be0a802db6b<br>Related: OS#4311<br>Change-Id: Idb4215fa2f364e28c0bb73fb9975b6c9f50a46f6<br>---<br>M src/logging.c<br>1 file changed, 6 insertions(+), 36 deletions(-)<br><br></pre><pre style="font-family: monospace,monospace; white-space: pre-wrap;">git pull ssh://gerrit.osmocom.org:29418/libosmocore refs/changes/89/26089/1</pre><pre style="font-family: monospace,monospace; white-space: pre-wrap;"><span>diff --git a/src/logging.c b/src/logging.c</span><br><span>index 00d75c3..9e2f5c2 100644</span><br><span>--- a/src/logging.c</span><br><span>+++ b/src/logging.c</span><br><span>@@ -1090,34 +1090,21 @@</span><br><span> </span><br><span> /*! switch from non-blocking/write-queue to blocking + buffered stream output</span><br><span> * \param[in] target log target which we should switch</span><br><span style="color: hsl(0, 100%, 40%);">- * \return 0 on success; 1 if already switched before; negative on error */</span><br><span style="color: hsl(120, 100%, 40%);">+ * \return 0 on success; 1 if already switched before; negative on error</span><br><span style="color: hsl(120, 100%, 40%);">+ * Must be called with mutex osmo_log_tgt_mutex held, see log_tgt_mutex_lock.</span><br><span style="color: hsl(120, 100%, 40%);">+ */</span><br><span> int log_target_file_switch_to_stream(struct log_target *target)</span><br><span> {</span><br><span> struct osmo_wqueue *wq;</span><br><span style="color: hsl(0, 100%, 40%);">- const char *name;</span><br><span> </span><br><span> if (!target)</span><br><span> return -ENODEV;</span><br><span> </span><br><span style="color: hsl(0, 100%, 40%);">- /* this only works for file/stderr targets */</span><br><span style="color: hsl(0, 100%, 40%);">- switch (target->type) {</span><br><span style="color: hsl(0, 100%, 40%);">- case LOG_TGT_TYPE_FILE:</span><br><span style="color: hsl(0, 100%, 40%);">- name = target->tgt_file.fname;</span><br><span style="color: hsl(0, 100%, 40%);">- break;</span><br><span style="color: hsl(0, 100%, 40%);">- case LOG_TGT_TYPE_STDERR:</span><br><span style="color: hsl(0, 100%, 40%);">- name = "stderr";</span><br><span style="color: hsl(0, 100%, 40%);">- break;</span><br><span style="color: hsl(0, 100%, 40%);">- default:</span><br><span style="color: hsl(0, 100%, 40%);">- return -EINVAL;</span><br><span style="color: hsl(0, 100%, 40%);">- }</span><br><span style="color: hsl(0, 100%, 40%);">-</span><br><span> if (target->tgt_file.out) {</span><br><span> /* target has already been switched over */</span><br><span> return 1;</span><br><span> }</span><br><span> </span><br><span style="color: hsl(0, 100%, 40%);">- LOGP(DLGLOBAL, LOGL_INFO, "Switching log target '%s' to blocking stream I/O\n", name);</span><br><span style="color: hsl(0, 100%, 40%);">-</span><br><span> wq = target->tgt_file.wqueue;</span><br><span> OSMO_ASSERT(wq);</span><br><span> </span><br><span>@@ -1127,8 +1114,6 @@</span><br><span> else</span><br><span> target->tgt_file.out = fopen(target->tgt_file.fname, "a");</span><br><span> if (!target->tgt_file.out) {</span><br><span style="color: hsl(0, 100%, 40%);">- LOGP(DLGLOBAL, LOGL_ERROR, "Cannot open log target '%s' as blocking stream I/O: %s\n",</span><br><span style="color: hsl(0, 100%, 40%);">- name, strerror(errno));</span><br><span> return -EIO;</span><br><span> }</span><br><span> </span><br><span>@@ -1156,35 +1141,22 @@</span><br><span> </span><br><span> /*! switch from blocking + buffered file output to non-blocking write-queue based output.</span><br><span> * \param[in] target log target which we should switch</span><br><span style="color: hsl(0, 100%, 40%);">- * \return 0 on success; 1 if already switched before; negative on error */</span><br><span style="color: hsl(120, 100%, 40%);">+ * \return 0 on success; 1 if already switched before; negative on error</span><br><span style="color: hsl(120, 100%, 40%);">+ * Must be called with mutex osmo_log_tgt_mutex held, see log_tgt_mutex_lock.</span><br><span style="color: hsl(120, 100%, 40%);">+ */</span><br><span> int log_target_file_switch_to_wqueue(struct log_target *target)</span><br><span> {</span><br><span> struct osmo_wqueue *wq;</span><br><span style="color: hsl(0, 100%, 40%);">- const char *name;</span><br><span> int rc;</span><br><span> </span><br><span> if (!target)</span><br><span> return -ENODEV;</span><br><span> </span><br><span style="color: hsl(0, 100%, 40%);">- /* this only works for file/stderr targets */</span><br><span style="color: hsl(0, 100%, 40%);">- switch (target->type) {</span><br><span style="color: hsl(0, 100%, 40%);">- case LOG_TGT_TYPE_FILE:</span><br><span style="color: hsl(0, 100%, 40%);">- name = target->tgt_file.fname;</span><br><span style="color: hsl(0, 100%, 40%);">- break;</span><br><span style="color: hsl(0, 100%, 40%);">- case LOG_TGT_TYPE_STDERR:</span><br><span style="color: hsl(0, 100%, 40%);">- name = "stderr";</span><br><span style="color: hsl(0, 100%, 40%);">- break;</span><br><span style="color: hsl(0, 100%, 40%);">- default:</span><br><span style="color: hsl(0, 100%, 40%);">- return -EINVAL;</span><br><span style="color: hsl(0, 100%, 40%);">- }</span><br><span style="color: hsl(0, 100%, 40%);">-</span><br><span> if (!target->tgt_file.out) {</span><br><span> /* target has already been switched over */</span><br><span> return 1;</span><br><span> }</span><br><span> </span><br><span style="color: hsl(0, 100%, 40%);">- LOGP(DLGLOBAL, LOGL_INFO, "Switching log target '%s' to non-blocking I/O\n", name);</span><br><span style="color: hsl(0, 100%, 40%);">-</span><br><span> /* we create a ~640kB sized talloc pool within the write-queue to ensure individual</span><br><span> * log lines (stored as msgbs) will not put result in malloc() calls, and also to</span><br><span> * reduce the OOM probability within logging, as the pool is already allocated */</span><br><span>@@ -1198,8 +1170,6 @@</span><br><span> if (target->type == LOG_TGT_TYPE_FILE) {</span><br><span> rc = open(target->tgt_file.fname, O_WRONLY|O_APPEND|O_CREAT|O_NONBLOCK, 0660);</span><br><span> if (rc < 0) {</span><br><span style="color: hsl(0, 100%, 40%);">- LOGP(DLGLOBAL, LOGL_ERROR, "Cannot open log target '%s' as non-blocking I/O: %s\n",</span><br><span style="color: hsl(0, 100%, 40%);">- name, strerror(errno));</span><br><span> talloc_free(wq);</span><br><span> return -errno;</span><br><span> }</span><br><span></span><br></pre><p>To view, visit <a href="https://gerrit.osmocom.org/c/libosmocore/+/26089">change 26089</a>. 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<div style="display:none"> Gerrit-Project: libosmocore </div>
<div style="display:none"> Gerrit-Branch: master </div>
<div style="display:none"> Gerrit-Change-Id: Idb4215fa2f364e28c0bb73fb9975b6c9f50a46f6 </div>
<div style="display:none"> Gerrit-Change-Number: 26089 </div>
<div style="display:none"> Gerrit-PatchSet: 1 </div>
<div style="display:none"> Gerrit-Owner: pespin <pespin@sysmocom.de> </div>
<div style="display:none"> Gerrit-MessageType: newchange </div>