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Make sbuf_drain safe for external use

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While sbuf_drain was an internal function, two
KASSERTS checked the sanity of it being called.
However, an external caller may be ignorant if
there is any data to drain, or if an error has
already accumulated. Be nice and return immediately
with the accumulated error.

MFC after: 2 weeks
Reviewed By: tuexen, #transport
Sponsored by: NetApp, Inc.
Differential Revision: https://reviews.freebsd.org/D29544
This commit is contained in:
Richard Scheffenegger 2021-04-02 20:11:45 +02:00
parent 36d6e65722
commit cad4fd0365
1 changed files with 6 additions and 2 deletions
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8
sys/kern/subr_sbuf.c
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@ -388,8 +388,12 @@ sbuf_drain(struct sbuf *s)
{
int len;
KASSERT(s->s_len > 0, ("Shouldn't drain empty sbuf %p", s));
KASSERT(s->s_error == 0, ("Called %s with error on %p", __func__, s));
/*
* Immediately return when no work to do,
* or an error has already been accumulated.
*/
if ((s->s_len == 0) || (s->s_error != 0))
return(s->s_error);
if (SBUF_DODRAINTOEOR(s) && s->s_rec_off == 0)
return (s->s_error = EDEADLK);