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passt/packet.h
David Gibson 38bcce9977 packet: Rework packet_get() versus packet_get_try()
Most failures of packet_get() indicate a serious problem, and log messages
accordingly.  However, a few callers expect failures here, because they're
probing for a certain range which might or might not be in a packet.  They
use packet_get_try() which passes a NULL func to packet_get_do() to
suppress the logging which is unwanted in this case.

However, this doesn't just suppress the log when packet_get_do() finds the
requested region isn't in the packet.  It suppresses logging for all other
errors too, which do indicate serious problems, even for the callers of
packet_get_try().  Worse it will pass the NULL func on to
packet_check_range() which doesn't expect it, meaning we'll get unhelpful
messages from there if there is a failure.

Fix this by making packet_get_try_do() the primary function which doesn't
log for the case of a range outside the packet.  packet_get_do() becomes a
trivial wrapper around that which logs a message if packet_get_try_do()
returns NULL.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
2025-03-20 20:33:22 +01:00

83 lines
2.5 KiB
C

/* SPDX-License-Identifier: GPL-2.0-or-later
* Copyright (c) 2022 Red Hat GmbH
* Author: Stefano Brivio <sbrivio@redhat.com>
*/
#ifndef PACKET_H
#define PACKET_H
#include <stdbool.h>
/* Maximum size of a single packet stored in pool, including headers */
#define PACKET_MAX_LEN ((size_t)UINT16_MAX)
/**
* struct pool - Generic pool of packets stored in a buffer
* @buf: Buffer storing packet descriptors,
* a struct vu_dev_region array for passt vhost-user mode
* @buf_size: Total size of buffer,
* 0 for passt vhost-user mode
* @size: Number of usable descriptors for the pool
* @count: Number of used descriptors for the pool
* @pkt: Descriptors: see macros below
*/
struct pool {
char *buf;
size_t buf_size;
size_t size;
size_t count;
struct iovec pkt[];
};
int vu_packet_check_range(void *buf, const char *ptr, size_t len);
void packet_add_do(struct pool *p, size_t len, const char *start,
const char *func, int line);
void *packet_get_try_do(const struct pool *p, const size_t idx,
size_t offset, size_t len, size_t *left,
const char *func, int line);
void *packet_get_do(const struct pool *p, const size_t idx,
size_t offset, size_t len, size_t *left,
const char *func, int line);
bool pool_full(const struct pool *p);
void pool_flush(struct pool *p);
#define packet_add(p, len, start) \
packet_add_do(p, len, start, __func__, __LINE__)
#define packet_get_try(p, idx, offset, len, left) \
packet_get_try_do(p, idx, offset, len, left, __func__, __LINE__)
#define packet_get(p, idx, offset, len, left) \
packet_get_do(p, idx, offset, len, left, __func__, __LINE__)
#define PACKET_POOL_DECL(_name, _size, _buf) \
struct _name ## _t { \
char *buf; \
size_t buf_size; \
size_t size; \
size_t count; \
struct iovec pkt[_size]; \
}
#define PACKET_POOL_INIT_NOCAST(_size, _buf, _buf_size) \
{ \
.buf_size = _buf_size, \
.buf = _buf, \
.size = _size, \
}
#define PACKET_POOL(name, size, buf, buf_size) \
PACKET_POOL_DECL(name, size, buf) name = \
PACKET_POOL_INIT_NOCAST(size, buf, buf_size)
#define PACKET_INIT(name, size, buf, buf_size) \
(struct name ## _t) PACKET_POOL_INIT_NOCAST(size, buf, buf_size)
#define PACKET_POOL_NOINIT(name, size, buf) \
PACKET_POOL_DECL(name, size, buf) name ## _storage; \
static struct pool *name = (struct pool *)&name ## _storage
#define PACKET_POOL_P(name, size, buf, buf_size) \
PACKET_POOL(name ## _storage, size, buf, buf_size); \
struct pool *name = (struct pool *)&name ## _storage
#endif /* PACKET_H */