bpf(4) doesn't have to keep track of nonblocking state itself

[David Gwynne]

vfs does it for us.

ok?

Index: bpf.c
===================================================================
RCS file: /cvs/src/sys/net/bpf.c,v
retrieving revision 1.202
diff -u -p -r1.202 bpf.c
--- bpf.c       17 Jan 2021 02:27:29 -0000      1.202
+++ bpf.c       19 Jan 2021 00:10:22 -0000
@@ -379,7 +379,6 @@ bpfopen(dev_t dev, int flag, int mode, s
        sigio_init(&bd->bd_sigio);
 
        bd->bd_rtout = 0;       /* no timeout by default */
-       bd->bd_rnonblock = ISSET(flag, FNONBLOCK);
 
        bpf_get(bd);
        LIST_INSERT_HEAD(&bpf_d_list, bd, bd_list);
@@ -497,7 +496,7 @@ bpfread(dev_t dev, struct uio *uio, int 
                        ROTATE_BUFFERS(d);
                        break;
                }
-               if (d->bd_rnonblock) {
+               if (ISSET(ioflag, IO_NDELAY)) {
                        /* User requested non-blocking I/O */
                        error = EWOULDBLOCK;
                } else if (d->bd_rtout == 0) {
@@ -982,10 +981,7 @@ bpfioctl(dev_t dev, u_long cmd, caddr_t 
                break;
 
        case FIONBIO:           /* Non-blocking I/O */
-               if (*(int *)addr)
-                       d->bd_rnonblock = 1;
-               else
-                       d->bd_rnonblock = 0;
+               /* let vfs to keep track of this */
                break;
 
        case FIOASYNC:          /* Send signal on receive packets */
Index: bpfdesc.h
===================================================================
RCS file: /cvs/src/sys/net/bpfdesc.h,v
retrieving revision 1.44
diff -u -p -r1.44 bpfdesc.h
--- bpfdesc.h   2 Jan 2021 02:46:06 -0000       1.44
+++ bpfdesc.h   19 Jan 2021 00:10:22 -0000
@@ -80,7 +80,6 @@ struct bpf_d {
        struct bpf_if  *bd_bif;         /* interface descriptor */
        uint64_t        bd_rtout;       /* [m] Read timeout in nanoseconds */
        u_long          bd_nreaders;    /* [m] # threads asleep in bpfread() */
-       int             bd_rnonblock;   /* true if nonblocking reads are set */
        struct bpf_program_smr
                       *bd_rfilter;     /* read filter code */
        struct bpf_program_smr