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[Qemu-devel] [PATCH v2 31/42] ivshmem: Simplify how we cope with short r
From: |
Markus Armbruster |
Subject: |
[Qemu-devel] [PATCH v2 31/42] ivshmem: Simplify how we cope with short reads from server |
Date: |
Mon, 7 Mar 2016 20:25:43 +0100 |
Short reads from a UNIX domain sockets are exceedingly unlikely when
the other side always sends eight bytes and we always read eight
bytes. We cope with them anyway. However, the code doing that is
rather convoluted. Dumb it down radically.
Signed-off-by: Markus Armbruster <address@hidden>
---
hw/misc/ivshmem.c | 75 ++++++++++++-------------------------------------------
1 file changed, 16 insertions(+), 59 deletions(-)
diff --git a/hw/misc/ivshmem.c b/hw/misc/ivshmem.c
index 2b14daa..ef4249b 100644
--- a/hw/misc/ivshmem.c
+++ b/hw/misc/ivshmem.c
@@ -26,7 +26,6 @@
#include "migration/migration.h"
#include "qemu/error-report.h"
#include "qemu/event_notifier.h"
-#include "qemu/fifo8.h"
#include "sysemu/char.h"
#include "sysemu/hostmem.h"
#include "qapi/visitor.h"
@@ -80,7 +79,6 @@ typedef struct IVShmemState {
uint32_t intrstatus;
CharDriverState *server_chr;
- Fifo8 incoming_fifo;
MemoryRegion ivshmem_mmio;
/* We might need to register the BAR before we actually have the memory.
@@ -99,6 +97,8 @@ typedef struct IVShmemState {
uint32_t vectors;
uint32_t features;
MSIVector *msi_vectors;
+ uint64_t msg_buf; /* buffer for receiving server messages */
+ int msg_buffered_bytes; /* #bytes in @msg_buf */
Error *migration_blocker;
@@ -255,11 +255,6 @@ static const MemoryRegionOps ivshmem_mmio_ops = {
},
};
-static int ivshmem_can_receive(void * opaque)
-{
- return sizeof(int64_t);
-}
-
static void ivshmem_vector_notify(void *opaque)
{
MSIVector *entry = opaque;
@@ -459,53 +454,6 @@ static void resize_peers(IVShmemState *s, int nb_peers)
}
}
-static bool fifo_update_and_get(IVShmemState *s, const uint8_t *buf, int size,
- void *data, size_t len)
-{
- const uint8_t *p;
- uint32_t num;
-
- assert(len <= sizeof(int64_t)); /* limitation of the fifo */
- if (fifo8_is_empty(&s->incoming_fifo) && size == len) {
- memcpy(data, buf, size);
- return true;
- }
-
- IVSHMEM_DPRINTF("short read of %d bytes\n", size);
-
- num = MIN(size, sizeof(int64_t) - fifo8_num_used(&s->incoming_fifo));
- fifo8_push_all(&s->incoming_fifo, buf, num);
-
- if (fifo8_num_used(&s->incoming_fifo) < len) {
- assert(num == 0);
- return false;
- }
-
- size -= num;
- buf += num;
- p = fifo8_pop_buf(&s->incoming_fifo, len, &num);
- assert(num == len);
-
- memcpy(data, p, len);
-
- if (size > 0) {
- fifo8_push_all(&s->incoming_fifo, buf, size);
- }
-
- return true;
-}
-
-static bool fifo_update_and_get_i64(IVShmemState *s,
- const uint8_t *buf, int size, int64_t *i64)
-{
- if (fifo_update_and_get(s, buf, size, i64, sizeof(*i64))) {
- *i64 = GINT64_FROM_LE(*i64);
- return true;
- }
-
- return false;
-}
-
static void ivshmem_add_kvm_msi_virq(IVShmemState *s, int vector,
Error **errp)
{
@@ -658,6 +606,14 @@ static void process_msg(IVShmemState *s, int64_t msg, int
fd, Error **errp)
}
}
+static int ivshmem_can_receive(void *opaque)
+{
+ IVShmemState *s = opaque;
+
+ assert(s->msg_buffered_bytes < sizeof(s->msg_buf));
+ return sizeof(s->msg_buf) - s->msg_buffered_bytes;
+}
+
static void ivshmem_read(void *opaque, const uint8_t *buf, int size)
{
IVShmemState *s = opaque;
@@ -665,9 +621,14 @@ static void ivshmem_read(void *opaque, const uint8_t *buf,
int size)
int fd;
int64_t msg;
- if (!fifo_update_and_get_i64(s, buf, size, &msg)) {
+ assert(size >= 0 && s->msg_buffered_bytes + size <= sizeof(s->msg_buf));
+ memcpy((unsigned char *)&s->msg_buf + s->msg_buffered_bytes, buf, size);
+ s->msg_buffered_bytes += size;
+ if (s->msg_buffered_bytes < sizeof(s->msg_buf)) {
return;
}
+ msg = le64_to_cpu(s->msg_buf);
+ s->msg_buffered_bytes = 0;
fd = qemu_chr_fe_get_msgfd(s->server_chr);
IVSHMEM_DPRINTF("posn is %" PRId64 ", fd is %d\n", msg, fd);
@@ -1018,8 +979,6 @@ static void pci_ivshmem_realize(PCIDevice *dev, Error
**errp)
}
}
- fifo8_create(&s->incoming_fifo, sizeof(int64_t));
-
if (s->role_val == IVSHMEM_PEER) {
error_setg(&s->migration_blocker,
"Migration is disabled when using feature 'peer mode' in
device 'ivshmem'");
@@ -1032,8 +991,6 @@ static void pci_ivshmem_exit(PCIDevice *dev)
IVShmemState *s = IVSHMEM(dev);
int i;
- fifo8_destroy(&s->incoming_fifo);
-
if (s->migration_blocker) {
migrate_del_blocker(s->migration_blocker);
error_free(s->migration_blocker);
--
2.4.3
- [Qemu-devel] [PATCH v2 15/42] ivshmem: Clean up after commit 9940c32, (continued)
- [Qemu-devel] [PATCH v2 15/42] ivshmem: Clean up after commit 9940c32, Markus Armbruster, 2016/03/07
- [Qemu-devel] [PATCH v2 18/42] ivshmem: Fix harmless misuse of Error, Markus Armbruster, 2016/03/07
- [Qemu-devel] [PATCH v2 27/42] ivshmem: Receive shared memory synchronously in realize(), Markus Armbruster, 2016/03/07
- [Qemu-devel] [PATCH v2 32/42] ivshmem: Tighten check of property "size", Markus Armbruster, 2016/03/07
- [Qemu-devel] [PATCH v2 26/42] ivshmem: Plug leaks on unplug, fix peer disconnect, Markus Armbruster, 2016/03/07
- [Qemu-devel] [PATCH v2 37/42] ivshmem: Replace int role_val by OnOffAuto master, Markus Armbruster, 2016/03/07
- [Qemu-devel] [PATCH v2 39/42] ivshmem: Clean up after the previous commit, Markus Armbruster, 2016/03/07
- [Qemu-devel] [PATCH v2 31/42] ivshmem: Simplify how we cope with short reads from server,
Markus Armbruster <=
- [Qemu-devel] [PATCH v2 29/42] ivshmem: Rely on server sending the ID right after the version, Markus Armbruster, 2016/03/07
- [Qemu-devel] [PATCH v2 38/42] ivshmem: Split ivshmem-plain, ivshmem-doorbell off ivshmem, Markus Armbruster, 2016/03/07
- [Qemu-devel] [PATCH v2 30/42] ivshmem: Drop the hackish test for UNIX domain chardev, Markus Armbruster, 2016/03/07
- [Qemu-devel] [PATCH v2 17/42] ivshmem: Don't destroy the chardev on version mismatch, Markus Armbruster, 2016/03/07
- Re: [Qemu-devel] [PATCH v2 00/42] ivshmem: Fixes, cleanups, device model split, Paolo Bonzini, 2016/03/08
- Re: [Qemu-devel] [PATCH v2 00/42] ivshmem: Fixes, cleanups, device model split, Paolo Bonzini, 2016/03/08