Author: cem
Date: Wed Aug 7 19:25:56 2019
New Revision: 350692
URL: https://svnweb.freebsd.org/changeset/base/350692
Log:
sbuf(9): Refactor sbuf_newbuf into sbuf_new
Code flow was somewhat difficult to read due to the combination of
multiple return sites and the 4x possible dynamic constructions of an
sbuf. (Future consideration: do we need all 4?) Refactored slightly to
improve legibility.
No functional change.
Sponsored by: Dell EMC Isilon
Modified:
head/sys/kern/subr_sbuf.c
Modified: head/sys/kern/subr_sbuf.c
==============================================================================
--- head/sys/kern/subr_sbuf.c Wed Aug 7 19:23:07 2019 (r350691)
+++ head/sys/kern/subr_sbuf.c Wed Aug 7 19:25:56 2019 (r350692)
@@ -187,39 +187,6 @@ sbuf_extend(struct sbuf *s, int addlen)
}
/*
- * Initialize the internals of an sbuf.
- * If buf is non-NULL, it points to a static or already-allocated string
- * big enough to hold at least length characters.
- */
-static struct sbuf *
-sbuf_newbuf(struct sbuf *s, char *buf, int length, int flags)
-{
-
- memset(s, 0, sizeof(*s));
- s->s_flags = flags;
- s->s_size = length;
- s->s_buf = buf;
-
- if (!SBUF_CANEXTEND(s)) {
- KASSERT(s->s_size >= SBUF_MINSIZE,
- ("attempt to create an sbuf smaller than %d bytes",
- SBUF_MINSIZE));
- }
-
- if (s->s_buf != NULL)
- return (s);
-
- if (SBUF_CANEXTEND(s))
- s->s_size = sbuf_extendsize(s->s_size);
-
- s->s_buf = SBMALLOC(s->s_size, SBUF_MALLOCFLAG(s));
- if (s->s_buf == NULL)
- return (NULL);
- SBUF_SETFLAG(s, SBUF_DYNAMIC);
- return (s);
-}
-
-/*
* Initialize an sbuf.
* If buf is non-NULL, it points to a static or already-allocated string
* big enough to hold at least length characters.
@@ -232,19 +199,52 @@ sbuf_new(struct sbuf *s, char *buf, int length, int fl
("attempt to create an sbuf of negative length (%d)", length));
KASSERT((flags & ~SBUF_USRFLAGMSK) == 0,
("%s called with invalid flags", __func__));
+ KASSERT((flags & SBUF_AUTOEXTEND) || length >= SBUF_MINSIZE,
+ ("sbuf buffer %d smaller than minimum %d bytes", length,
+ SBUF_MINSIZE));
flags &= SBUF_USRFLAGMSK;
- if (s != NULL)
- return (sbuf_newbuf(s, buf, length, flags));
- s = SBMALLOC(sizeof(*s), (flags & SBUF_NOWAIT) ? M_NOWAIT : M_WAITOK);
- if (s == NULL)
- return (NULL);
- if (sbuf_newbuf(s, buf, length, flags) == NULL) {
- SBFREE(s);
- return (NULL);
+ /*
+ * Allocate 'DYNSTRUCT' sbuf from the heap, if NULL 's' was provided.
+ */
+ if (s == NULL) {
+ s = SBMALLOC(sizeof(*s),
+ (flags & SBUF_NOWAIT) ? M_NOWAIT : M_WAITOK);
+ if (s == NULL)
+ goto out;
+ SBUF_SETFLAG(s, SBUF_DYNSTRUCT);
+ } else {
+ /*
+ * DYNSTRUCT SBMALLOC sbufs are allocated with M_ZERO, but
+ * user-provided sbuf objects must be initialized.
+ */
+ memset(s, 0, sizeof(*s));
}
- SBUF_SETFLAG(s, SBUF_DYNSTRUCT);
+
+ s->s_flags |= flags;
+ s->s_size = length;
+ s->s_buf = buf;
+
+ /*
+ * Allocate DYNAMIC, i.e., heap data buffer backing the sbuf, if no
+ * buffer was provided.
+ */
+ if (s->s_buf == NULL) {
+ if (SBUF_CANEXTEND(s))
+ s->s_size = sbuf_extendsize(s->s_size);
+ s->s_buf = SBMALLOC(s->s_size, SBUF_MALLOCFLAG(s));
+ if (s->s_buf == NULL)
+ goto out;
+ SBUF_SETFLAG(s, SBUF_DYNAMIC);
+ }
+
+out:
+ if (s != NULL && s->s_buf == NULL) {
+ if (SBUF_ISDYNSTRUCT(s))
+ SBFREE(s);
+ s = NULL;
+ }
return (s);
}
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