<html><body><div style="font-family: times new roman, new york, times, serif; font-size: 12pt; color: #000000"><hr id="zwchr"><blockquote style="border-left:2px solid #1010FF;margin-left:5px;padding-left:5px;color:#000;font-weight:normal;font-style:normal;text-decoration:none;font-family:Helvetica,Arial,sans-serif;font-size:12pt;" data-mce-style="border-left: 2px solid #1010FF; margin-left: 5px; padding-left: 5px; color: #000; font-weight: normal; font-style: normal; text-decoration: none; font-family: Helvetica,Arial,sans-serif; font-size: 12pt;"><b>From: </b>"zhenyu.ren" <zhenyu.ren@aliyun.com><br><b>To: </b>"Mathieu Desnoyers" <mathieu.desnoyers@efficios.com>, "David Goulet" <dgoulet@efficios.com><br><b>Cc: </b>"lttng-dev" <lttng-dev@lists.lttng.org><br><b>Sent: </b>Tuesday, October 22, 2013 4:49:19 AM<br><b>Subject: </b>答复: 答复: lttng list -u coredump<br><div><br></div><div class="__aliyun_email_body_block"><div style="" data-mce-style=""><br></div><div class="__aliyun_signature_wrap">><span style="font-family: 'times new roman', 'new york', times, serif; font-size: 16px; line-height: 24px; " data-mce-style="font-family: 'times new roman', 'new york', times, serif; font-size: 16px; line-height: 24px;">Therefore, the &(pos)->member != NULL check will break out of the loop immediately,</span><br><div><br></div></div><div class="__aliyun_signature_wrap">As you pointed out,pos is a very large pointer value(i.e <span style="color: rgb(51, 51, 51); font-size: 13px; line-height: 19px; " data-mce-style="color: #333333; font-size: 13px; line-height: 19px;"> 0xffffffffffffff88,say</span> an invalid pointer) . Before check itself, <span style="font-family: 'times new roman', 'new york', times, serif; font-size: 16px; line-height: 24px; " data-mce-style="font-family: 'times new roman', 'new york', times, serif; font-size: 16px; line-height: 24px;">&(pos)->member has been deferenced anyway.</span></div></div></blockquote><div>Can you point out what in the C99 specification makes you believe that the pointer is actually dereferenced in the expression "&(pos)->member" ?<br></div><div><br></div><div>AFAIK, this only evaluates to the address of field "member" within "pos". The compiler should not dereference the pointer "pos" at all.<br></div><div><br></div><div>I'm concerned that focusing on the hash table iteration might be leading us in the wrong direction. What we see in the information you provided is a an error detected by glibc "free()", which seems much more likely to point to the culprit. However, we'd need more information about the symbols in this backtrace. Probably that getting it with a lttng-sessiond compiled with "-g -O0" (no optimisations, with debug symbols) would help us make more sense out of the free() error output.<br></div><div><br></div><div>Thanks,<br></div><div><br></div><div>Mathieu<br></div><div><br></div><blockquote style="border-left:2px solid #1010FF;margin-left:5px;padding-left:5px;color:#000;font-weight:normal;font-style:normal;text-decoration:none;font-family:Helvetica,Arial,sans-serif;font-size:12pt;" data-mce-style="border-left: 2px solid #1010FF; margin-left: 5px; padding-left: 5px; color: #000; font-weight: normal; font-style: normal; text-decoration: none; font-family: Helvetica,Arial,sans-serif; font-size: 12pt;"><div class="__aliyun_email_body_block"><div class="__aliyun_signature_wrap"><span style="color: rgb(51, 51, 51); font-size: 13px; line-height: 19px; " data-mce-style="color: #333333; font-size: 13px; line-height: 19px;"><br></span></div><div class="__aliyun_signature_wrap"><span style="font-family: 'times new roman', 'new york', times, serif; font-size: 16px; line-height: 24px; " data-mce-style="font-family: 'times new roman', 'new york', times, serif; font-size: 16px; line-height: 24px;"><br></span></div><div class="__aliyun_signature_wrap"><span style="font-family: 'times new roman', 'new york', times, serif; font-size: 16px; line-height: 24px; " data-mce-style="font-family: 'times new roman', 'new york', times, serif; font-size: 16px; line-height: 24px;">><span style="font-family: 'times new roman', 'new york', times, serif; font-size: 16px; line-height: 24px; " data-mce-style="font-family: 'times new roman', 'new york', times, serif; font-size: 16px; line-height: 24px;">Please provide details about the lttng-tools, lttng-ust, lttng-modules, userspace RCU versions you are using</span></span></div><div class="__aliyun_signature_wrap"><span style="font-family: 'times new roman', 'new york', times, serif; font-size: 16px; line-height: 24px; " data-mce-style="font-family: 'times new roman', 'new york', times, serif; font-size: 16px; line-height: 24px;"><br></span></div><div class="__aliyun_signature_wrap"><span style="font-family: 'times new roman', 'new york', times, serif; font-size: 16px; line-height: 24px; " data-mce-style="font-family: 'times new roman', 'new york', times, serif; font-size: 16px; line-height: 24px;">lttng-tools,lttng-ust and lttng-modules are 2.3.0,userspace RCU is 0.8.0</span></div></div></blockquote><blockquote style="border-left:2px solid #1010FF;margin-left:5px;padding-left:5px;color:#000;font-weight:normal;font-style:normal;text-decoration:none;font-family:Helvetica,Arial,sans-serif;font-size:12pt;" data-mce-style="border-left: 2px solid #1010FF; margin-left: 5px; padding-left: 5px; color: #000; font-weight: normal; font-style: normal; text-decoration: none; font-family: Helvetica,Arial,sans-serif; font-size: 12pt;"><div class="__aliyun_email_body_block"><div class="__aliyun_signature_wrap"><span style="font-family: 'times new roman', 'new york', times, serif; font-size: 16px; line-height: 24px; " data-mce-style="font-family: 'times new roman', 'new york', times, serif; font-size: 16px; line-height: 24px;">thanks</span></div><div class="__aliyun_signature_wrap"><span style="font-family: 'times new roman', 'new york', times, serif; font-size: 16px; line-height: 24px; " data-mce-style="font-family: 'times new roman', 'new york', times, serif; font-size: 16px; line-height: 24px;">zhenyu.ren</span></div><div class="__aliyun_previous_quote"><div style="font-family: times new roman , new york , times , serif;font-size: 12.0pt;color: #000000;" data-mce-style="font-family: times new roman , new york , times , serif; font-size: 12.0pt; color: #000000;"><div><br></div></div></div></div></blockquote><div><br><div><br></div></div><div><br></div><div>-- <br></div><div><span name="x"></span>Mathieu Desnoyers<br>EfficiOS Inc.<br>http://www.efficios.com<span name="x"></span><br></div></div></body></html>