<p>fixeria has uploaded this change for <strong>review</strong>.</p><p><a href="https://gerrit.osmocom.org/c/osmo-bts/+/24594">View Change</a></p><pre style="font-family: monospace,monospace; white-space: pre-wrap;">l1sap: fix TDMA frame number wrap in l1sap_info_time_ind()<br><br>Using the normal arithmetic for TDMA frame numbers may result<br>in getting wrong values.  Consider the following situation:<br><br>  'info_time_ind->fn' is 0 (beginning of period)<br>   'bts->gsm_time.fn' is 2715647 (end of period)<br><br>With these input values the following expression:<br><br>  info_time_ind->fn - bts->gsm_time.fn<br><br>will be equal to:<br><br>  0 - 2715647 or -2715647<br><br>In this case osmo-bts does not log an error, because:<br><br>  if (-2715647 > 0) // is false<br><br>As a consequence, we do not increment number of RACH slots that<br>have passed by since the last time indication:<br><br>  for (i = 0; i < -2715647; i++) // is false<br><br>This is why we introduced GSM_TDMA_FN_{SUB,SUM,DIFF,INC} API.<br><br>Change-Id: I6168dd75daea50bbe2e19338e637185ac9ac87ef<br>---<br>M src/common/l1sap.c<br>1 file changed, 4 insertions(+), 4 deletions(-)<br><br></pre><pre style="font-family: monospace,monospace; white-space: pre-wrap;">git pull ssh://gerrit.osmocom.org:29418/osmo-bts refs/changes/94/24594/1</pre><pre style="font-family: monospace,monospace; white-space: pre-wrap;"><span>diff --git a/src/common/l1sap.c b/src/common/l1sap.c</span><br><span>index b17bf01..cd2af57 100644</span><br><span>--- a/src/common/l1sap.c</span><br><span>+++ b/src/common/l1sap.c</span><br><span>@@ -592,17 +592,17 @@</span><br><span>                               struct osmo_phsap_prim *l1sap,</span><br><span>                               struct info_time_ind_param *info_time_ind)</span><br><span> {</span><br><span style="color: hsl(0, 100%, 40%);">-  int frames_expired;</span><br><span style="color: hsl(0, 100%, 40%);">-     int i;</span><br><span style="color: hsl(120, 100%, 40%);">+        unsigned int frames_expired;</span><br><span style="color: hsl(120, 100%, 40%);">+  unsigned int i;</span><br><span> </span><br><span>  DEBUGPFN(DL1P, info_time_ind->fn, "Rx MPH_INFO time ind\n");</span><br><span> </span><br><span>        /* Calculate and check frame difference */</span><br><span style="color: hsl(0, 100%, 40%);">-      frames_expired = info_time_ind->fn - bts->gsm_time.fn;</span><br><span style="color: hsl(120, 100%, 40%);">+  frames_expired = GSM_TDMA_FN_SUB(info_time_ind->fn, bts->gsm_time.fn);</span><br><span>         if (frames_expired > 1) {</span><br><span>                 if (bts->gsm_time.fn)</span><br><span>                     LOGPFN(DL1P, LOGL_ERROR, info_time_ind->fn,</span><br><span style="color: hsl(0, 100%, 40%);">-                       "Invalid condition detected: Frame difference is %"PRIu32"-%"PRIu32"=%d > 1!\n",</span><br><span style="color: hsl(120, 100%, 40%);">+                             "Invalid condition detected: Frame difference is %"PRIu32"-%"PRIu32"=%u > 1!\n",</span><br><span>                            info_time_ind->fn, bts->gsm_time.fn, frames_expired);</span><br><span>     }</span><br><span> </span><br><span></span><br></pre><p>To view, visit <a href="https://gerrit.osmocom.org/c/osmo-bts/+/24594">change 24594</a>. To unsubscribe, or for help writing mail filters, visit <a href="https://gerrit.osmocom.org/settings">settings</a>.</p><div itemscope itemtype="http://schema.org/EmailMessage"><div itemscope itemprop="action" itemtype="http://schema.org/ViewAction"><link itemprop="url" href="https://gerrit.osmocom.org/c/osmo-bts/+/24594"/><meta itemprop="name" content="View Change"/></div></div>

<div style="display:none"> Gerrit-Project: osmo-bts </div>
<div style="display:none"> Gerrit-Branch: master </div>
<div style="display:none"> Gerrit-Change-Id: I6168dd75daea50bbe2e19338e637185ac9ac87ef </div>
<div style="display:none"> Gerrit-Change-Number: 24594 </div>
<div style="display:none"> Gerrit-PatchSet: 1 </div>
<div style="display:none"> Gerrit-Owner: fixeria <vyanitskiy@sysmocom.de> </div>
<div style="display:none"> Gerrit-MessageType: newchange </div>