<?xml version="1.0" encoding="ANSI_X3.4-1968" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968" /><title>ata_scsi_error()</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /><link rel="home" href="index.html" title="libATA Developer's Guide" /><link rel="up" href="ch03.html" title="Chapter 3. Error handling" /><link rel="prev" href="ch03s04.html" title="How commands are completed" /><link rel="next" href="ch03s06.html" title="Problems with the current EH" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">ata_scsi_error()</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ch03s04.html">Prev</a> </td><th width="60%" align="center">Chapter 3. Error handling</th><td width="20%" align="right"> <a accesskey="n" href="ch03s06.html">Next</a></td></tr></table><hr /></div><div class="sect1" title="ata_scsi_error()"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="id2843964"></a>ata_scsi_error()</h2></div></div></div><p> ata_scsi_error() is the current transportt->eh_strategy_handler() for libata. As discussed above, this will be entered in two cases - timeout and ATAPI error completion. This function calls low level libata driver's eng_timeout() callback, the standard callback for which is ata_eng_timeout(). It checks if a qc is active and calls ata_qc_timeout() on the qc if so. Actual error handling occurs in ata_qc_timeout(). </p><p> If EH is invoked for timeout, ata_qc_timeout() stops BMDMA and completes the qc. Note that as we're currently in EH, we cannot call scsi_done. As described in SCSI EH doc, a recovered scmd should be either retried with scsi_queue_insert() or finished with scsi_finish_command(). Here, we override qc->scsidone with scsi_finish_command() and calls ata_qc_complete(). </p><p> If EH is invoked due to a failed ATAPI qc, the qc here is completed but not deallocated. The purpose of this half-completion is to use the qc as place holder to make EH code reach this place. This is a bit hackish, but it works. </p><p> Once control reaches here, the qc is deallocated by invoking __ata_qc_complete() explicitly. Then, internal qc for REQUEST SENSE is issued. Once sense data is acquired, scmd is finished by directly invoking scsi_finish_command() on the scmd. Note that as we already have completed and deallocated the qc which was associated with the scmd, we don't need to/cannot call ata_qc_complete() again. </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ch03s04.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="ch03.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="ch03s06.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">How commands are completed </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Problems with the current EH</td></tr></table></div></body></html>
