diff mbox series

[v7,1/4] migration/multifd: Stop changing the packet on recv side

Message ID 20240828145650.15879-2-farosas@suse.de
State New
Headers show
Series migration/multifd: Remove multifd_send_state->pages (leftovers) | expand

Commit Message

Fabiano Rosas Aug. 28, 2024, 2:56 p.m. UTC 
As observed by Philippe, the multifd_ram_unfill_packet() function
currently leaves the MultiFDPacket structure with mixed
endianness. This is harmless, but ultimately not very clean.

Stop touching the received packet and do the necessary work using
stack variables instead.

While here tweak the error strings and fix the space before
semicolons. Also remove the "100 times bigger" comment because it's
just one possible explanation for a size mismatch and it doesn't even
match the code.

CC: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
---
 migration/multifd-nocomp.c | 29 ++++++++++++-----------------
 migration/multifd.c        | 20 +++++++++-----------
 2 files changed, 21 insertions(+), 28 deletions(-)

Comments

Peter Xu Aug. 28, 2024, 3:59 p.m. UTC | #1 
On Wed, Aug 28, 2024 at 11:56:47AM -0300, Fabiano Rosas wrote:
> As observed by Philippe, the multifd_ram_unfill_packet() function
> currently leaves the MultiFDPacket structure with mixed
> endianness. This is harmless, but ultimately not very clean.
> 
> Stop touching the received packet and do the necessary work using
> stack variables instead.
> 
> While here tweak the error strings and fix the space before
> semicolons. Also remove the "100 times bigger" comment because it's
> just one possible explanation for a size mismatch and it doesn't even
> match the code.
> 
> CC: Philippe Mathieu-Daudé <philmd@linaro.org>
> Signed-off-by: Fabiano Rosas <farosas@suse.de>

Reviewed-by: Peter Xu <peterx@redhat.com>
diff mbox series

Patch

diff --git a/migration/multifd-nocomp.c b/migration/multifd-nocomp.c
index f294d1b0b2..07c63f4a72 100644
--- a/migration/multifd-nocomp.c
+++ b/migration/multifd-nocomp.c
@@ -220,33 +220,28 @@  int multifd_ram_unfill_packet(MultiFDRecvParams *p, Error **errp)
     MultiFDPacket_t *packet = p->packet;
     uint32_t page_count = multifd_ram_page_count();
     uint32_t page_size = multifd_ram_page_size();
+    uint32_t pages_per_packet = be32_to_cpu(packet->pages_alloc);
     int i;
 
-    packet->pages_alloc = be32_to_cpu(packet->pages_alloc);
-    /*
-     * If we received a packet that is 100 times bigger than expected
-     * just stop migration.  It is a magic number.
-     */
-    if (packet->pages_alloc > page_count) {
-        error_setg(errp, "multifd: received packet "
-                   "with size %u and expected a size of %u",
-                   packet->pages_alloc, page_count) ;
+    if (pages_per_packet > page_count) {
+        error_setg(errp, "multifd: received packet with %u pages, expected %u",
+                   pages_per_packet, page_count);
         return -1;
     }
 
     p->normal_num = be32_to_cpu(packet->normal_pages);
-    if (p->normal_num > packet->pages_alloc) {
-        error_setg(errp, "multifd: received packet "
-                   "with %u normal pages and expected maximum pages are %u",
-                   p->normal_num, packet->pages_alloc) ;
+    if (p->normal_num > pages_per_packet) {
+        error_setg(errp, "multifd: received packet with %u non-zero pages, "
+                   "which exceeds maximum expected pages %u",
+                   p->normal_num, pages_per_packet);
         return -1;
     }
 
     p->zero_num = be32_to_cpu(packet->zero_pages);
-    if (p->zero_num > packet->pages_alloc - p->normal_num) {
-        error_setg(errp, "multifd: received packet "
-                   "with %u zero pages and expected maximum zero pages are %u",
-                   p->zero_num, packet->pages_alloc - p->normal_num) ;
+    if (p->zero_num > pages_per_packet - p->normal_num) {
+        error_setg(errp,
+                   "multifd: received packet with %u zero pages, expected maximum %u",
+                   p->zero_num, pages_per_packet - p->normal_num);
         return -1;
     }
 
diff --git a/migration/multifd.c b/migration/multifd.c
index b89715fdc2..2a8cd9174c 100644
--- a/migration/multifd.c
+++ b/migration/multifd.c
@@ -230,22 +230,20 @@  void multifd_send_fill_packet(MultiFDSendParams *p)
 
 static int multifd_recv_unfill_packet(MultiFDRecvParams *p, Error **errp)
 {
-    MultiFDPacket_t *packet = p->packet;
+    const MultiFDPacket_t *packet = p->packet;
+    uint32_t magic = be32_to_cpu(packet->magic);
+    uint32_t version = be32_to_cpu(packet->version);
     int ret = 0;
 
-    packet->magic = be32_to_cpu(packet->magic);
-    if (packet->magic != MULTIFD_MAGIC) {
-        error_setg(errp, "multifd: received packet "
-                   "magic %x and expected magic %x",
-                   packet->magic, MULTIFD_MAGIC);
+    if (magic != MULTIFD_MAGIC) {
+        error_setg(errp, "multifd: received packet magic %x, expected %x",
+                   magic, MULTIFD_MAGIC);
         return -1;
     }
 
-    packet->version = be32_to_cpu(packet->version);
-    if (packet->version != MULTIFD_VERSION) {
-        error_setg(errp, "multifd: received packet "
-                   "version %u and expected version %u",
-                   packet->version, MULTIFD_VERSION);
+    if (version != MULTIFD_VERSION) {
+        error_setg(errp, "multifd: received packet version %u, expected %u",
+                   version, MULTIFD_VERSION);
         return -1;
     }