[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH XTF v4] Implement pv_read_some
On 24/07/17 07:24, Felix Schmoll wrote: > Implement reading from PV console. Making use of polling. > > Signed-off-by: Felix Schmoll <eggi.innovations@xxxxxxxxx> > > --- > Changed since v3: > * Add to comment: read function blocks if no data available > --- > common/console.c | 26 ++++++++++++++++++++++++++ > include/xtf/console.h | 2 ++ > 2 files changed, 28 insertions(+) > > diff --git a/common/console.c b/common/console.c > index 7cb2361..b1a35f4 100644 > --- a/common/console.c > +++ b/common/console.c > @@ -46,6 +46,32 @@ static size_t pv_console_write_some(const char *buf, > size_t len) > } > > /* > + * Read out data from the pv ring, either until buffer is filled or no > + * more data are available. Might result in partial strings, depending > + * on how xenconsoled passes in data. > + * > + * Will block if no data are available. > + */ > +size_t pv_console_read_some(char *buf, size_t len) > +{ > + size_t s = 0; > + uint32_t cons, prod; > + > + while ( !test_and_clear_bit(pv_evtchn, shared_info.evtchn_pending) || > + (pv_ring->in_cons == pv_ring->in_prod) ) > + hypercall_poll(pv_evtchn); > + > + cons = pv_ring->in_cons, prod = LOAD_ACQUIRE(&pv_ring->in_prod); Given the confusion this has caused on IRC, I'd prefer that the code was explicit. Is the following ok? cons = pv_ring->in_cons; prod = LOAD_ACQUIRE(&pv_ring->in_prod); If so, I can fix up on commit. ~Andrew > + > + while ( (s < len) && (0 < (prod - cons)) ) > + buf[s++] = pv_ring->in[cons++ & (sizeof(pv_ring->in) - 1)]; > + > + STORE_RELEASE(&pv_ring->in_cons, cons); > + > + return s; > +} > + > +/* > * Write some data into the pv ring, synchronously waiting for all data to be > * consumed. > */ > diff --git a/include/xtf/console.h b/include/xtf/console.h > index 2a93c06..caec790 100644 > --- a/include/xtf/console.h > +++ b/include/xtf/console.h > @@ -25,6 +25,8 @@ void init_pv_console(xencons_interface_t *ring, > void vprintk(const char *fmt, va_list args) __printf(1, 0); > void printk(const char *fmt, ...) __printf(1, 2); > > +size_t pv_console_read_some(char *buf, size_t len); > + > #endif /* XTF_CONSOLE_H */ > > /* _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
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