Author: rwatson
Date: Wed Feb 25 13:17:46 2009
New Revision: 189034
URL: http://svn.freebsd.org/changeset/base/189034
Log:
Merge r184534 from head to stable/7:
Allow a single read(2) system call on an audit pipe to retrieve data from
more than one audit record at a time in order to improve efficiency.
Sponsored by: Apple, Inc.
Modified:
stable/7/sys/ (props changed)
stable/7/sys/contrib/pf/ (props changed)
stable/7/sys/dev/ath/ath_hal/ (props changed)
stable/7/sys/dev/cxgb/ (props changed)
stable/7/sys/security/audit/audit_pipe.c
Modified: stable/7/sys/security/audit/audit_pipe.c
==============================================================================
--- stable/7/sys/security/audit/audit_pipe.c Wed Feb 25 12:32:15 2009
(r189033)
+++ stable/7/sys/security/audit/audit_pipe.c Wed Feb 25 13:17:46 2009
(r189034)
@@ -934,19 +934,8 @@ audit_pipe_ioctl(struct cdev *dev, u_lon
}
/*
- * Audit pipe read. Pull one record off the queue and copy to user space.
- * On error, the record is dropped.
- *
- * Providing more sophisticated behavior, such as partial reads, is tricky
- * due to the potential for parallel I/O. If partial read support is
- * required, it will require a per-pipe "current record being read" along
- * with an offset into that trecord which has already been read. Threads
- * performing partial reads will need to allocate per-thread copies of the
- * data so that if another thread completes the read of the record, it can be
- * freed without adding reference count logic. If this is added, a flag to
- * indicate that only atomic record reads are desired would be useful, as if
- * different threads are all waiting for records on the pipe, they will want
- * independent record reads, which is currently the behavior.
+ * Audit pipe read. Read one or more partial or complete records to user
+ * memory.
*/
static int
audit_pipe_read(struct cdev *dev, struct uio *uio, int flag)
@@ -982,40 +971,43 @@ audit_pipe_read(struct cdev *dev, struct
/*
* Copy as many remaining bytes from the current record to userspace
- * as we can.
+ * as we can. Keep processing records until we run out of records in
+ * the queue, or until the user buffer runs out of space.
*
* Note: we rely on the SX lock to maintain ape's stability here.
*/
ap->ap_reads++;
- ape = TAILQ_FIRST(&ap->ap_queue);
- toread = MIN(ape->ape_record_len - ape->ape_record_offset,
- uio->uio_resid);
- AUDIT_PIPE_UNLOCK(ap);
- error = uiomove((char *)ape->ape_record + ape->ape_record_offset,
- toread, uio);
- if (error) {
- AUDIT_PIPE_SX_XUNLOCK(ap);
- return (error);
- }
+ while ((ape = TAILQ_FIRST(&ap->ap_queue)) != NULL &&
+ uio->uio_resid > 0) {
+ AUDIT_PIPE_LOCK_ASSERT(ap);
- /*
- * If the copy succeeded, update book-keeping, and if no bytes remain
- * in the current record, free it.
- */
- AUDIT_PIPE_LOCK(ap);
- KASSERT(TAILQ_FIRST(&ap->ap_queue) == ape,
- ("audit_pipe_read: queue out of sync after uiomove"));
- ape->ape_record_offset += toread;
- if (ape->ape_record_offset == ape->ape_record_len) {
- TAILQ_REMOVE(&ap->ap_queue, ape, ape_queue);
- ap->ap_qlen--;
- } else
- ape = NULL;
+ toread = MIN(ape->ape_record_len - ape->ape_record_offset,
+ uio->uio_resid);
+ AUDIT_PIPE_UNLOCK(ap);
+ error = uiomove((char *)ape->ape_record +
+ ape->ape_record_offset, toread, uio);
+ if (error) {
+ AUDIT_PIPE_SX_XUNLOCK(ap);
+ return (error);
+ }
+
+ /*
+ * If the copy succeeded, update book-keeping, and if no
+ * bytes remain in the current record, free it.
+ */
+ AUDIT_PIPE_LOCK(ap);
+ KASSERT(TAILQ_FIRST(&ap->ap_queue) == ape,
+ ("audit_pipe_read: queue out of sync after uiomove"));
+ ape->ape_record_offset += toread;
+ if (ape->ape_record_offset == ape->ape_record_len) {
+ TAILQ_REMOVE(&ap->ap_queue, ape, ape_queue);
+ audit_pipe_entry_free(ape);
+ ap->ap_qlen--;
+ }
+ }
AUDIT_PIPE_UNLOCK(ap);
AUDIT_PIPE_SX_XUNLOCK(ap);
- if (ape != NULL)
- audit_pipe_entry_free(ape);
- return (error);
+ return (0);
}
/*
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