Re: recvmsg() "short receive" after FIONREAD
- Reply: Andriy Gapon : "Re: recvmsg() "short receive" after FIONREAD"
- In reply to: Mark Johnston : "Re: recvmsg() "short receive" after FIONREAD"
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Date: Sat, 11 Sep 2021 14:16:23 UTC
On 11/09/2021 17:13, Mark Johnston wrote: > I think the semantic change is ok. Did you change FIONREAD to lock the > sockbuf? I think it would be necessary to avoid races with pulseaudio: > sb_acc is modified before sb_ctl, so there could be windows where > sbavail(sb) - sb->sb_ctl gives a larger. > > And, it is not really safe to lock the sockbuf itself, since it may be > overwritten by a listen(2) call. SOCK_RECVBUF_LOCK(so) should be used > instead. I didn't think about the locking, so I didn't add it. My current patch is trivial: @@ -210,7 +210,7 @@ soo_ioctl(struct file *fp, u_long cmd, void *data, struct ucred *active_cred, if (SOLISTENING(so)) { error = EINVAL; } else { - *(int *)data = sbavail(&so->so_rcv); + *(int *)data = sbavail(&so->so_rcv) - so->so_rcv.sb_ctl; } break; Let me try adding the lock. Thank you again! -- Andriy Gapon