svn commit: r361953 - stable/12/sys/cam/ctl
Alexander Motin
mav at FreeBSD.org
Tue Jun 9 02:03:31 UTC 2020
Author: mav
Date: Tue Jun 9 02:03:30 2020
New Revision: 361953
URL: https://svnweb.freebsd.org/changeset/base/361953
Log:
MFC r361630: Remove session locking from cfiscsi_pdu_update_cmdsn().
cs_cmdsn can be incremented with single atomic. expcmdsn/maxcmdsn set in
cfiscsi_pdu_prepare() based on cs_cmdsn are not required to be updated
synchronously, only monotonically, that is achieved with lock there.
Modified:
stable/12/sys/cam/ctl/ctl_frontend_iscsi.c
Directory Properties:
stable/12/ (props changed)
Modified: stable/12/sys/cam/ctl/ctl_frontend_iscsi.c
==============================================================================
--- stable/12/sys/cam/ctl/ctl_frontend_iscsi.c Tue Jun 9 02:01:39 2020 (r361952)
+++ stable/12/sys/cam/ctl/ctl_frontend_iscsi.c Tue Jun 9 02:03:30 2020 (r361953)
@@ -211,7 +211,7 @@ cfiscsi_pdu_update_cmdsn(const struct icl_pdu *request
{
const struct iscsi_bhs_scsi_command *bhssc;
struct cfiscsi_session *cs;
- uint32_t cmdsn, expstatsn;
+ uint32_t cmdsn, curcmdsn;
cs = PDU_SESSION(request);
@@ -220,16 +220,20 @@ cfiscsi_pdu_update_cmdsn(const struct icl_pdu *request
* The purpose of the timeout is to reset the connection when it stalls;
* we don't want this to happen when NOP-In or NOP-Out ends up delayed
* in some queue.
- *
- * XXX: Locking?
*/
cs->cs_timeout = 0;
/*
+ * Immediate commands carry cmdsn, but it is neither incremented nor
+ * verified.
+ */
+ if (request->ip_bhs->bhs_opcode & ISCSI_BHS_OPCODE_IMMEDIATE)
+ return (false);
+
+ /*
* Data-Out PDUs don't contain CmdSN.
*/
- if ((request->ip_bhs->bhs_opcode & ~ISCSI_BHS_OPCODE_IMMEDIATE) ==
- ISCSI_BHS_OPCODE_SCSI_DATA_OUT)
+ if (request->ip_bhs->bhs_opcode == ISCSI_BHS_OPCODE_SCSI_DATA_OUT)
return (false);
/*
@@ -237,50 +241,37 @@ cfiscsi_pdu_update_cmdsn(const struct icl_pdu *request
* (initiator -> target) PDUs.
*/
bhssc = (const struct iscsi_bhs_scsi_command *)request->ip_bhs;
- cmdsn = ntohl(bhssc->bhssc_cmdsn);
- expstatsn = ntohl(bhssc->bhssc_expstatsn);
+ curcmdsn = cmdsn = ntohl(bhssc->bhssc_cmdsn);
- CFISCSI_SESSION_LOCK(cs);
-#if 0
- if (expstatsn != cs->cs_statsn) {
- CFISCSI_SESSION_DEBUG(cs, "received PDU with ExpStatSN %d, "
- "while current StatSN is %d", expstatsn,
- cs->cs_statsn);
- }
-#endif
+ /*
+ * Increment session cmdsn and exit if we received the expected value.
+ */
+ do {
+ if (atomic_fcmpset_32(&cs->cs_cmdsn, &curcmdsn, cmdsn + 1))
+ return (false);
+ } while (curcmdsn == cmdsn);
- if ((request->ip_bhs->bhs_opcode & ISCSI_BHS_OPCODE_IMMEDIATE) == 0) {
- /*
- * The target MUST silently ignore any non-immediate command
- * outside of this range.
- */
- if (ISCSI_SNLT(cmdsn, cs->cs_cmdsn) ||
- ISCSI_SNGT(cmdsn, cs->cs_cmdsn - 1 + maxtags)) {
- CFISCSI_SESSION_UNLOCK(cs);
- CFISCSI_SESSION_WARN(cs, "received PDU with CmdSN %u, "
- "while expected %u", cmdsn, cs->cs_cmdsn);
- return (true);
- }
-
- /*
- * We don't support multiple connections now, so any
- * discontinuity in CmdSN means lost PDUs. Since we don't
- * support PDU retransmission -- terminate the connection.
- */
- if (cmdsn != cs->cs_cmdsn) {
- CFISCSI_SESSION_UNLOCK(cs);
- CFISCSI_SESSION_WARN(cs, "received PDU with CmdSN %u, "
- "while expected %u; dropping connection",
- cmdsn, cs->cs_cmdsn);
- cfiscsi_session_terminate(cs);
- return (true);
- }
- cs->cs_cmdsn++;
+ /*
+ * The target MUST silently ignore any non-immediate command outside
+ * of this range.
+ */
+ if (ISCSI_SNLT(cmdsn, curcmdsn) ||
+ ISCSI_SNGT(cmdsn, curcmdsn - 1 + maxtags)) {
+ CFISCSI_SESSION_WARN(cs, "received PDU with CmdSN %u, "
+ "while expected %u", cmdsn, curcmdsn);
+ return (true);
}
- CFISCSI_SESSION_UNLOCK(cs);
-
- return (false);
+ /*
+ * We don't support multiple connections now, so any discontinuity in
+ * CmdSN means lost PDUs. Since we don't support PDU retransmission --
+ * terminate the connection.
+ */
+ CFISCSI_SESSION_WARN(cs, "received PDU with CmdSN %u, "
+ "while expected %u; dropping connection",
+ cmdsn, curcmdsn);
+ cfiscsi_session_terminate(cs);
+ return (true);
}
static void
@@ -367,6 +358,7 @@ cfiscsi_pdu_prepare(struct icl_pdu *response)
struct cfiscsi_session *cs;
struct iscsi_bhs_scsi_response *bhssr;
bool advance_statsn = true;
+ uint32_t cmdsn;
cs = PDU_SESSION(response);
@@ -408,8 +400,9 @@ cfiscsi_pdu_prepare(struct icl_pdu *response)
if (bhssr->bhssr_opcode != ISCSI_BHS_OPCODE_SCSI_DATA_IN ||
(bhssr->bhssr_flags & BHSDI_FLAGS_S))
bhssr->bhssr_statsn = htonl(cs->cs_statsn);
- bhssr->bhssr_expcmdsn = htonl(cs->cs_cmdsn);
- bhssr->bhssr_maxcmdsn = htonl(cs->cs_cmdsn - 1 +
+ cmdsn = cs->cs_cmdsn;
+ bhssr->bhssr_expcmdsn = htonl(cmdsn);
+ bhssr->bhssr_maxcmdsn = htonl(cmdsn - 1 +
imax(0, maxtags - cs->cs_outstanding_ctl_pdus));
if (advance_statsn)
@@ -2461,19 +2454,14 @@ cfiscsi_datamove_in(union ctl_io *io)
buffer_offset = io->scsiio.kern_rel_offset;
/*
- * This is the transfer length expected by the initiator. In theory,
- * it could be different from the correct amount of data from the SCSI
- * point of view, even if that doesn't make any sense.
+ * This is the transfer length expected by the initiator. It can be
+ * different from the amount of data from the SCSI point of view.
*/
expected_len = ntohl(bhssc->bhssc_expected_data_transfer_length);
-#if 0
- if (expected_len != io->scsiio.kern_total_len) {
- CFISCSI_SESSION_DEBUG(cs, "expected transfer length %zd, "
- "actual length %zd", expected_len,
- (size_t)io->scsiio.kern_total_len);
- }
-#endif
+ /*
+ * If the transfer is outside of expected length -- we are done.
+ */
if (buffer_offset >= expected_len) {
#if 0
CFISCSI_SESSION_DEBUG(cs, "buffer_offset = %zd, "
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