linux/include/scsi/scsi_bsg_iscsi.h
Gustavo A. R. Silva 5febf6d6ae scsi: Replace zero-length array with flexible-array member
The current codebase makes use of the zero-length array language extension
to the C90 standard, but the preferred mechanism to declare variable-length
types such as these ones is a flexible array member[1][2], introduced in
C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning in
case the flexible array does not occur last in the structure, which will
help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by this
change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Link: https://lore.kernel.org/r/20200224161406.GA21454@embeddedor
Reviewed-by: Lee Duncan <lduncan@suse.com>
Reviewed-by: Satish Kharat <satishkh@cisco.com>
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2020-03-11 23:07:56 -04:00

97 lines
2.2 KiB
C

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* iSCSI Transport BSG Interface
*
* Copyright (C) 2009 James Smart, Emulex Corporation
*/
#ifndef SCSI_BSG_ISCSI_H
#define SCSI_BSG_ISCSI_H
/*
* This file intended to be included by both kernel and user space
*/
#include <scsi/scsi.h>
/*
* iSCSI Transport SGIO v4 BSG Message Support
*/
/* Default BSG request timeout (in seconds) */
#define ISCSI_DEFAULT_BSG_TIMEOUT (10 * HZ)
/*
* Request Message Codes supported by the iSCSI Transport
*/
/* define the class masks for the message codes */
#define ISCSI_BSG_CLS_MASK 0xF0000000 /* find object class */
#define ISCSI_BSG_HST_MASK 0x80000000 /* iscsi host class */
/* iscsi host Message Codes */
#define ISCSI_BSG_HST_VENDOR (ISCSI_BSG_HST_MASK | 0x000000FF)
/*
* iSCSI Host Messages
*/
/* ISCSI_BSG_HST_VENDOR : */
/* Request:
* Note: When specifying vendor_id, be sure to read the Vendor Type and ID
* formatting requirements specified in scsi_netlink.h
*/
struct iscsi_bsg_host_vendor {
/*
* Identifies the vendor that the message is formatted for. This
* should be the recipient of the message.
*/
uint64_t vendor_id;
/* start of vendor command area */
uint32_t vendor_cmd[];
};
/* Response:
*/
struct iscsi_bsg_host_vendor_reply {
/* start of vendor response area */
uint32_t vendor_rsp[0];
};
/* request (CDB) structure of the sg_io_v4 */
struct iscsi_bsg_request {
uint32_t msgcode;
union {
struct iscsi_bsg_host_vendor h_vendor;
} rqst_data;
} __attribute__((packed));
/* response (request sense data) structure of the sg_io_v4 */
struct iscsi_bsg_reply {
/*
* The completion result. Result exists in two forms:
* if negative, it is an -Exxx system errno value. There will
* be no further reply information supplied.
* else, it's the 4-byte scsi error result, with driver, host,
* msg and status fields. The per-msgcode reply structure
* will contain valid data.
*/
uint32_t result;
/* If there was reply_payload, how much was recevied ? */
uint32_t reply_payload_rcv_len;
union {
struct iscsi_bsg_host_vendor_reply vendor_reply;
} reply_data;
};
#endif /* SCSI_BSG_ISCSI_H */