Hi Dan,
Thanks for reading the code...
That loop would normally exit via the break at line 775;
if there were exactly count entries, that break avoids count being decremented
to -1, so count remains zero.
if the loop is ever terminated by the while, then either/or:
- if there were more than count entries, then count is a relatively small
positive number;
- if the END entry was missing, then count wraps to -1 (~0), and line 780/781
prints all F's.
i.e. if count is not zero at line 779, then the template was wrong (too many
entries, or no END entry).
( btw: yes, the redundant test for missing END entry at line 783 was added
later than the while loop )
Regards
Joe
-Original Message-
From: Dan Carpenter [mailto:dan.carpen...@oracle.com]
Sent: Tuesday, December 15, 2015 12:05 PM
To: Joe Carnuccio <joe.carnuc...@qlogic.com>
Cc: linux-scsi <linux-scsi@vger.kernel.org>
Subject: re: qla2xxx: ISP27xx add tests for incomplete template.
Hello Joe Carnuccio,
The patch 299f5e27ac5f: "qla2xxx: ISP27xx add tests for incomplete template."
from Sep 25, 2014, leads to the following static checker
warning:
drivers/scsi/qla2xxx/qla_tmpl.c:779 qla27xx_walk_template()
warn: should this be 'count == -1'
drivers/scsi/qla2xxx/qla_tmpl.c
764 static void
765 qla27xx_walk_template(struct scsi_qla_host *vha,
766 struct qla27xx_fwdt_template *tmp, void *buf, ulong *len)
767 {
768 struct qla27xx_fwdt_entry *ent = (void *)tmp +
tmp->entry_offset;
769 ulong count = tmp->entry_count;
770
771 ql_dbg(ql_dbg_misc, vha, 0xd01a,
772 "%s: entry count %lx\n", __func__, count);
773 while (count--) {
774 if (qla27xx_find_entry(ent->hdr.entry_type)(vha, ent,
buf, len))
775 break;
776 ent = qla27xx_next_entry(ent);
777 }
778
779 if (count)
780 ql_dbg(ql_dbg_misc, vha, 0xd018,
781 "%s: residual count (%lx)\n", __func__, count);
The static checker assumes that we are testing to see if the loop ended with a
break or not. These are normally bugs because if we did not break the count is
set to (ulong)-1.
This code is sort of weird. It's just debugging so I guess it doesn't matter.
Are we expecting -1?
782
783 if (ent->hdr.entry_type != ENTRY_TYPE_TMP_END)
784 ql_dbg(ql_dbg_misc, vha, 0xd019,
785 "%s: missing end (%lx)\n", __func__, count);
786
787 ql_dbg(ql_dbg_misc, vha, 0xd01b,
788 "%s: len=%lx\n", __func__, *len);
789
790 if (buf) {
791 ql_log(ql_log_warn, vha, 0xd015,
792 "Firmware dump saved to temp buffer (%ld/%p)\n",
793 vha->host_no, vha->hw->fw_dump);
794 qla2x00_post_uevent_work(vha, QLA_UEVENT_CODE_FW_DUMP);
795 }
796 }
regards,
dan carpenter
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