Author: scottl
Date: Tue Feb 6 06:55:55 2018
New Revision: 328919
URL: https://svnweb.freebsd.org/changeset/base/328919
Log:
Fix a case where a request frame can be composed that requires 2 or more
SGList elements, but there's only enough space in the request frame for
either 1 element or a chain frame pointer. Previously, the code would
hit the wrong case, add the SGList element, but then fail to add the
chain frame due to lack of space. Re-arrange the code to catch this case
earlier and handle it.
Sponsored by: Netflix
Modified:
head/sys/dev/mps/mps.c
Modified: head/sys/dev/mps/mps.c
==============================================================================
--- head/sys/dev/mps/mps.c Tue Feb 6 06:42:25 2018 (r328918)
+++ head/sys/dev/mps/mps.c Tue Feb 6 06:55:55 2018 (r328919)
@@ -2609,6 +2609,17 @@ mps_push_sge(struct mps_command *cm, void *sgep, size_
if (cm->cm_sglsize < MPS_SGC_SIZE)
panic("MPS: Need SGE Error Code\n");
+ if (segsleft >= 1 && cm->cm_sglsize < len + MPS_SGC_SIZE) {
+ /*
+ * 1 or more segment, enough room for only a chain.
+ * Hope the previous element wasn't a Simple entry
+ * that needed to be marked with
+ * MPI2_SGE_FLAGS_LAST_ELEMENT. Case (4).
+ */
+ if ((error = mps_add_chain(cm)) != 0)
+ return (error);
+ }
+
if (segsleft >= 2 &&
cm->cm_sglsize < len + MPS_SGC_SIZE + MPS_SGE64_SIZE) {
/*
@@ -2631,17 +2642,6 @@ mps_push_sge(struct mps_command *cm, void *sgep, size_
bcopy(sgep, cm->cm_sge, len);
cm->cm_sge = (MPI2_SGE_IO_UNION *)((uintptr_t)cm->cm_sge + len);
return (mps_add_chain(cm));
- }
-
- if (segsleft >= 1 && cm->cm_sglsize < len + MPS_SGC_SIZE) {
- /*
- * 1 or more segment, enough room for only a chain.
- * Hope the previous element wasn't a Simple entry
- * that needed to be marked with
- * MPI2_SGE_FLAGS_LAST_ELEMENT. Case (4).
- */
- if ((error = mps_add_chain(cm)) != 0)
- return (error);
}
#ifdef INVARIANTS
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