queue(3): Enhance queue debugging macros
Split the QUEUE_MACRO_DEBUG into QUEUE_MACRO_DEBUG_TRACE and QUEUE_MACRO_DEBUG_TRASH. Add the debug macrso QMD_IS_TRASHED() and QMD_SLIST_CHECK_PREVPTR(). Document these in queue.3. Reviewed by: emaste Sponsored by: Dell EMC Isilon Differential Revision: https://reviews.freebsd.org/D3984
This commit is contained in:
Conrad Meyer
parent
d3bfc7250f
commit
06b9366795
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UPDATING
6
UPDATING
@ -31,6 +31,12 @@ NOTE TO PEOPLE WHO THINK THAT FreeBSD 12.x IS SLOW:
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disable the most expensive debugging functionality run
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"ln -s 'abort:false,junk:false' /etc/malloc.conf".)
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20160908:
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The queue(3) debugging macro, QUEUE_MACRO_DEBUG, has been split into
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two separate components, QUEUE_MACRO_DEBUG_TRACE and
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QUEUE_MACRO_DEBUG_TRASH. Define both for the original
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QUEUE_MACRO_DEBUG behavior.
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20160824:
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r304787 changed some ioctl interfaces between the iSCSI userspace
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programs and the kernel. ctladm, ctld, iscsictl, and iscsid must be
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@ -106,6 +106,7 @@ MLINKS+= queue.3 LIST_CLASS_ENTRY.3 \
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queue.3 SLIST_REMOVE.3 \
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queue.3 SLIST_REMOVE_AFTER.3 \
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queue.3 SLIST_REMOVE_HEAD.3 \
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queue.3 SLIST_REMOVE_PREVPTR.3 \
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queue.3 SLIST_SWAP.3 \
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queue.3 STAILQ_CLASS_ENTRY.3 \
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queue.3 STAILQ_CLASS_HEAD.3 \
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@ -28,7 +28,7 @@
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.\" @(#)queue.3 8.2 (Berkeley) 1/24/94
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.\" $FreeBSD$
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.\"
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.Dd August 15, 2016
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.Dd September 8, 2016
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.Dt QUEUE 3
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.Os
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.Sh NAME
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@ -1284,6 +1284,50 @@ while (n1 != NULL) {
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}
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TAILQ_INIT(&head);
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.Ed
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.Sh DIAGNOSTICS
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When debugging
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.Nm queue(3) ,
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it can be useful to trace queue changes.
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To enable tracing, define the macro
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.Va QUEUE_MACRO_DEBUG_TRACE
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at compile time.
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.Pp
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It can also be useful to trash pointers that have been unlinked from a queue,
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to detect use after removal.
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To enable pointer trashing, define the macro
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.Va QUEUE_MACRO_DEBUG_TRASH
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at compile time.
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The macro
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.Fn QMD_IS_TRASHED "void *ptr"
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returns true if
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.Fa ptr
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has been trashed by the
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.Va QUEUE_MACRO_DEBUG_TRASH
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option.
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.Pp
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In the kernel (with
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.Va INVARIANTS
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enabled), the
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.Fn SLIST_REMOVE_PREVPTR
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macro is available to aid debugging:
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.Bl -hang -offset indent
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.It Fn SLIST_REMOVE_PREVPTR "TYPE **prev" "TYPE *elm" "SLIST_ENTRY NAME"
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.Pp
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Removes
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.Fa elm ,
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which must directly follow the element whose
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.Va &SLIST_NEXT()
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is
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.Fa prev ,
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from the SLIST.
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This macro validates that
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.Fa elm
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follows
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.Fa prev
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in
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.Va INVARIANTS
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mode.
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.El
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.Sh SEE ALSO
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.Xr tree 3
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.Sh HISTORY
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@ -113,6 +113,12 @@
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*
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*/
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#ifdef QUEUE_MACRO_DEBUG
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#warn Use QUEUE_MACRO_DEBUG_TRACE and/or QUEUE_MACRO_DEBUG_TRASH
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#define QUEUE_MACRO_DEBUG_TRACE
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#define QUEUE_MACRO_DEBUG_TRASH
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#endif
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#ifdef QUEUE_MACRO_DEBUG_TRACE
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/* Store the last 2 places the queue element or head was altered */
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struct qm_trace {
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unsigned long lastline;
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@ -123,8 +129,6 @@ struct qm_trace {
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#define TRACEBUF struct qm_trace trace;
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#define TRACEBUF_INITIALIZER { __LINE__, 0, __FILE__, NULL } ,
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#define TRASHIT(x) do {(x) = (void *)-1;} while (0)
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#define QMD_SAVELINK(name, link) void **name = (void *)&(link)
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#define QMD_TRACE_HEAD(head) do { \
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(head)->trace.prevline = (head)->trace.lastline; \
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@ -140,14 +144,26 @@ struct qm_trace {
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(elem)->trace.lastfile = __FILE__; \
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} while (0)
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#else
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#else /* !QUEUE_MACRO_DEBUG_TRACE */
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#define QMD_TRACE_ELEM(elem)
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#define QMD_TRACE_HEAD(head)
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#define QMD_SAVELINK(name, link)
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#define TRACEBUF
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#define TRACEBUF_INITIALIZER
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#endif /* QUEUE_MACRO_DEBUG_TRACE */
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#ifdef QUEUE_MACRO_DEBUG_TRASH
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#define TRASHIT(x) do {(x) = (void *)-1;} while (0)
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#define QMD_IS_TRASHED(x) ((x) == (void *)(intptr_t)-1)
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#else /* !QUEUE_MACRO_DEBUG_TRASH */
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#define TRASHIT(x)
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#endif /* QUEUE_MACRO_DEBUG */
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#define QMD_IS_TRASHED(x) 0
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#endif /* QUEUE_MACRO_DEBUG_TRASH */
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#if defined(QUEUE_MACRO_DEBUG_TRACE) || defined(QUEUE_MACRO_DEBUG_TRASH)
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#define QMD_SAVELINK(name, link) void **name = (void *)&(link)
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#else /* !QUEUE_MACRO_DEBUG_TRACE && !QUEUE_MACRO_DEBUG_TRASH */
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#define QMD_SAVELINK(name, link)
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#endif /* QUEUE_MACRO_DEBUG_TRACE || QUEUE_MACRO_DEBUG_TRASH */
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#ifdef __cplusplus
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/*
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@ -187,6 +203,16 @@ struct { \
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/*
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* Singly-linked List functions.
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*/
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#if (defined(_KERNEL) && defined(INVARIANTS))
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#define QMD_SLIST_CHECK_PREVPTR(prevp, elm) do { \
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if (*(prevp) != (elm)) \
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panic("Bad prevptr *(%p) == %p != %p", \
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(prevp), *(prevp), (elm)); \
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} while (0)
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#else
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#define QMD_SLIST_CHECK_PREVPTR(prevp, elm)
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#endif
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#define SLIST_CONCAT(head1, head2, type, field) do { \
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QUEUE_TYPEOF(type) *curelm = SLIST_FIRST(head1); \
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if (curelm == NULL) { \
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@ -268,6 +294,12 @@ struct { \
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SLIST_FIRST((head)) = SLIST_NEXT(SLIST_FIRST((head)), field); \
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} while (0)
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#define SLIST_REMOVE_PREVPTR(prevp, elm, field) do { \
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QMD_SLIST_CHECK_PREVPTR(prevp, elm); \
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*(prevp) = SLIST_NEXT(elm, field); \
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TRASHIT((elm)->field.sle_next); \
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} while (0)
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#define SLIST_SWAP(head1, head2, type) do { \
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QUEUE_TYPEOF(type) *swap_first = SLIST_FIRST(head1); \
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SLIST_FIRST(head1) = SLIST_FIRST(head2); \
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