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[pxe] Discard queued PXE UDP packets when under memory pressure 

The PXE UDP receive queue may grow without limit if the PXE NBP does
not call PXENV_UDP_READ sufficiently frequently.

Fix by implementing a cache discarder for received PXE UDP packets
(similar to the TCP cache discarder).

Reported-by: Tal Shorer <shorer@amazon.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
pull/859/head
Michael Brown 2023-01-23 22:20:36 +00:00
parent c5426cdaa9
commit 4bffe0f0d9
1 changed files with 26 additions and 0 deletions
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26
src/arch/x86/interface/pxe/pxe_udp.c
View File

@ -12,6 +12,7 @@
#include <ipxe/uaccess.h>
#include <ipxe/process.h>
#include <ipxe/netdevice.h>
#include <ipxe/malloc.h>
#include <realmode.h>
#include <pxe.h>
@ -482,3 +483,28 @@ struct pxe_api_call pxe_udp_api[] __pxe_api_call = {
PXE_API_CALL ( PXENV_UDP_READ, pxenv_udp_read,
struct s_PXENV_UDP_READ ),
};
/**
* Discard some cached PXE UDP data
*
* @ret discarded Number of cached items discarded
*/
static unsigned int pxe_udp_discard ( void ) {
struct io_buffer *iobuf;
unsigned int discarded = 0;
/* Try to discard the oldest received UDP packet */
iobuf = list_first_entry ( &pxe_udp.list, struct io_buffer, list );
if ( iobuf ) {
list_del ( &iobuf->list );
free_iob ( iobuf );
discarded++;
}
return discarded;
}
/** PXE UDP cache discarder */
struct cache_discarder pxe_udp_discarder __cache_discarder ( CACHE_NORMAL ) = {
.discard = pxe_udp_discard,
};