Antw: [EXT] [PATCH] scsi: Replace zero-length array with flexible-array member
Hi!
Personally I think variable-sized structures are a bad thing, independent of
the syntax being used.
30 years ago saving one indirection would have been an argument for such
structures, but nowadays?
Regards,
Ulrich
>>> "Gustavo A. R. Silva" schrieb am 24.02.2020 um
>>> 17:14
in Nachricht
<32123_1582744382_5E56C33B_32123_188_1_20200224161406.GA21454@embeddedor>:
> 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 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
>
> Signed-off-by: Gustavo A. R. Silva
> ---
> drivers/scsi/fnic/vnic_devcmd.h | 2 +-
> drivers/scsi/ipr.h | 6 +++---
> drivers/scsi/isci/sas.h | 2 +-
> drivers/scsi/mpt3sas/mpt3sas_scsih.c | 2 +-
> drivers/scsi/mvsas/mv_sas.h | 2 +-
> drivers/scsi/mvumi.h | 4 ++--
> drivers/scsi/pmcraid.h | 2 +-
> drivers/scsi/snic/vnic_devcmd.h | 2 +-
> drivers/scsi/stex.c | 2 +-
> include/scsi/iscsi_if.h | 10 +-
> include/scsi/scsi_bsg_iscsi.h| 2 +-
> include/scsi/scsi_device.h | 4 ++--
> include/scsi/scsi_host.h | 2 +-
> include/scsi/scsi_ioctl.h| 2 +-
> include/scsi/srp.h | 8
> include/uapi/scsi/scsi_bsg_fc.h | 2 +-
> 16 files changed, 27 insertions(+), 27 deletions(-)
>
> diff --git a/drivers/scsi/fnic/vnic_devcmd.h
> b/drivers/scsi/fnic/vnic_devcmd.h
> index c5dde556dc7c..c20d30e36dfc 100644
> --- a/drivers/scsi/fnic/vnic_devcmd.h
> +++ b/drivers/scsi/fnic/vnic_devcmd.h
> @@ -442,7 +442,7 @@ struct vnic_devcmd_notify {
> struct vnic_devcmd_provinfo {
> u8 oui[3];
> u8 type;
> - u8 data[0];
> + u8 data[];
> };
>
> /*
> diff --git a/drivers/scsi/ipr.h b/drivers/scsi/ipr.h
> index a67baeb36d1f..fd3929a19ab5 100644
> --- a/drivers/scsi/ipr.h
> +++ b/drivers/scsi/ipr.h
> @@ -451,12 +451,12 @@ struct ipr_config_table_hdr64 {
>
> struct ipr_config_table {
> struct ipr_config_table_hdr hdr;
> - struct ipr_config_table_entry dev[0];
> + struct ipr_config_table_entry dev[];
> }__attribute__((packed, aligned (4)));
>
> struct ipr_config_table64 {
> struct ipr_config_table_hdr64 hdr64;
> - struct ipr_config_table_entry64 dev[0];
> + struct ipr_config_table_entry64 dev[];
> }__attribute__((packed, aligned (8)));
>
> struct ipr_config_table_entry_wrapper {
> @@ -792,7 +792,7 @@ struct ipr_mode_page28 {
> struct ipr_mode_page_hdr hdr;
> u8 num_entries;
> u8 entry_length;
> - struct ipr_dev_bus_entry bus[0];
> + struct ipr_dev_bus_entry bus[];
> }__attribute__((packed));
>
> struct ipr_mode_page24 {
> diff --git a/drivers/scsi/isci/sas.h b/drivers/scsi/isci/sas.h
> index dc26b4aea99e..15d8f3631ab7 100644
> --- a/drivers/scsi/isci/sas.h
> +++ b/drivers/scsi/isci/sas.h
> @@ -201,7 +201,7 @@ struct smp_req {
> u8 func;/* byte 1 */
> u8 alloc_resp_len; /* byte 2 */
> u8 req_len; /* byte 3 */
> - u8 req_data[0];
> + u8 req_data[];
> } __packed;
>
> /*
> diff --git a/drivers/scsi/mpt3sas/mpt3sas_scsih.c
> b/drivers/scsi/mpt3sas/mpt3sas_scsih.c
> index c597d544eb39..778d5e6ce385 100644
> --- a/drivers/scsi/mpt3sas/mpt3sas_scsih.c
> +++ b/drivers/scsi/mpt3sas/mpt3sas_scsih.c
> @@ -207,7 +207,7 @@ struct fw_event_work {
> u8 ignore;
> u16 event;
> struct kref refcount;
> - charevent_data[0] __aligned(4);
> + charevent_data[] __aligned(4);
> };
>
> static void fw_event_work_free(struct kref *r)
> diff --git a/drivers/scsi/mvsas/mv_sas.h b/drivers/scsi/mvsas/mv_sas.h
> index 519edc796691..327fdd5ee962 100644
> --- a/drivers/scsi/mvsas/mv_sas.h
> +++ b/drivers/scsi/mvsas/mv_sas.h
> @@ -394,7 +394,7 @@ struct mvs_info {
> dma_addr_t bulk_buffer_dma1;
> #define TRASH_BUCKET_SIZE
[PATCH] 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 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva
---
drivers/scsi/fnic/vnic_devcmd.h | 2 +-
drivers/scsi/ipr.h | 6 +++---
drivers/scsi/isci/sas.h | 2 +-
drivers/scsi/mpt3sas/mpt3sas_scsih.c | 2 +-
drivers/scsi/mvsas/mv_sas.h | 2 +-
drivers/scsi/mvumi.h | 4 ++--
drivers/scsi/pmcraid.h | 2 +-
drivers/scsi/snic/vnic_devcmd.h | 2 +-
drivers/scsi/stex.c | 2 +-
include/scsi/iscsi_if.h | 10 +-
include/scsi/scsi_bsg_iscsi.h| 2 +-
include/scsi/scsi_device.h | 4 ++--
include/scsi/scsi_host.h | 2 +-
include/scsi/scsi_ioctl.h| 2 +-
include/scsi/srp.h | 8
include/uapi/scsi/scsi_bsg_fc.h | 2 +-
16 files changed, 27 insertions(+), 27 deletions(-)
diff --git a/drivers/scsi/fnic/vnic_devcmd.h b/drivers/scsi/fnic/vnic_devcmd.h
index c5dde556dc7c..c20d30e36dfc 100644
--- a/drivers/scsi/fnic/vnic_devcmd.h
+++ b/drivers/scsi/fnic/vnic_devcmd.h
@@ -442,7 +442,7 @@ struct vnic_devcmd_notify {
struct vnic_devcmd_provinfo {
u8 oui[3];
u8 type;
- u8 data[0];
+ u8 data[];
};
/*
diff --git a/drivers/scsi/ipr.h b/drivers/scsi/ipr.h
index a67baeb36d1f..fd3929a19ab5 100644
--- a/drivers/scsi/ipr.h
+++ b/drivers/scsi/ipr.h
@@ -451,12 +451,12 @@ struct ipr_config_table_hdr64 {
struct ipr_config_table {
struct ipr_config_table_hdr hdr;
- struct ipr_config_table_entry dev[0];
+ struct ipr_config_table_entry dev[];
}__attribute__((packed, aligned (4)));
struct ipr_config_table64 {
struct ipr_config_table_hdr64 hdr64;
- struct ipr_config_table_entry64 dev[0];
+ struct ipr_config_table_entry64 dev[];
}__attribute__((packed, aligned (8)));
struct ipr_config_table_entry_wrapper {
@@ -792,7 +792,7 @@ struct ipr_mode_page28 {
struct ipr_mode_page_hdr hdr;
u8 num_entries;
u8 entry_length;
- struct ipr_dev_bus_entry bus[0];
+ struct ipr_dev_bus_entry bus[];
}__attribute__((packed));
struct ipr_mode_page24 {
diff --git a/drivers/scsi/isci/sas.h b/drivers/scsi/isci/sas.h
index dc26b4aea99e..15d8f3631ab7 100644
--- a/drivers/scsi/isci/sas.h
+++ b/drivers/scsi/isci/sas.h
@@ -201,7 +201,7 @@ struct smp_req {
u8 func;/* byte 1 */
u8 alloc_resp_len; /* byte 2 */
u8 req_len; /* byte 3 */
- u8 req_data[0];
+ u8 req_data[];
} __packed;
/*
diff --git a/drivers/scsi/mpt3sas/mpt3sas_scsih.c
b/drivers/scsi/mpt3sas/mpt3sas_scsih.c
index c597d544eb39..778d5e6ce385 100644
--- a/drivers/scsi/mpt3sas/mpt3sas_scsih.c
+++ b/drivers/scsi/mpt3sas/mpt3sas_scsih.c
@@ -207,7 +207,7 @@ struct fw_event_work {
u8 ignore;
u16 event;
struct kref refcount;
- charevent_data[0] __aligned(4);
+ charevent_data[] __aligned(4);
};
static void fw_event_work_free(struct kref *r)
diff --git a/drivers/scsi/mvsas/mv_sas.h b/drivers/scsi/mvsas/mv_sas.h
index 519edc796691..327fdd5ee962 100644
--- a/drivers/scsi/mvsas/mv_sas.h
+++ b/drivers/scsi/mvsas/mv_sas.h
@@ -394,7 +394,7 @@ struct mvs_info {
dma_addr_t bulk_buffer_dma1;
#define TRASH_BUCKET_SIZE 0x2
void *dma_pool;
- struct mvs_slot_info slot_info[0];
+ struct mvs_slot_info slot_info[];
};
struct mvs_prv_info{
diff --git a/drivers/scsi/mvumi.h b/drivers/scsi/mvumi.h
index ec8cc2207536..60d5691fc4ab 100644
--- a/drivers/scsi/mvumi.h
+++ b/drivers/scsi/mvumi.h
@@ -130,7 +130,7 @@ enum {
struct mvumi_hotplug_event {
u16 size;
u8 dummy[2];
- u8 bitmap[0];
+ u8 bitmap[];
};
struct mvumi_driver_event {
@@ -290,7 +290,7 @@ struct mvumi_rsp_frame {
struct mvumi_ob_data {
struct list_head list;
-
Re: [PATCH] scsi: Replace zero-length array with flexible-array member
On 2/24/20 10:30, Lee Duncan wrote:
> On 2/24/20 8:14 AM, Gustavo A. R. Silva wrote:
>> 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 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
>>
>> Signed-off-by: Gustavo A. R. Silva
>> ---
>> ...
>> diff --git a/include/scsi/iscsi_if.h b/include/scsi/iscsi_if.h
>> index 92b11c7e0b4f..b0e240b10bf9 100644
>> --- a/include/scsi/iscsi_if.h
>> +++ b/include/scsi/iscsi_if.h
>> @@ -311,7 +311,7 @@ enum iscsi_param_type {
>> struct iscsi_param_info {
>> uint32_t len; /* Actual length of the param value */
>> uint16_t param; /* iscsi param */
>> -uint8_t value[0]; /* length sized value follows */
>> +uint8_t value[];/* length sized value follows */
>> } __packed;
>>
>> struct iscsi_iface_param_info {
>> @@ -320,7 +320,7 @@ struct iscsi_iface_param_info {
>> uint16_t param; /* iscsi param value */
>> uint8_t iface_type; /* IPv4 or IPv6 */
>> uint8_t param_type; /* iscsi_param_type */
>> -uint8_t value[0]; /* length sized value follows */
>> +uint8_t value[];/* length sized value follows */
>> } __packed;
>>
>> /*
>> @@ -697,7 +697,7 @@ enum iscsi_flashnode_param {
>> struct iscsi_flashnode_param_info {
>> uint32_t len; /* Actual length of the param */
>> uint16_t param; /* iscsi param value */
>> -uint8_t value[0]; /* length sized value follows */
>> +uint8_t value[];/* length sized value follows */
>> } __packed;
>>
>> enum iscsi_discovery_parent_type {
>> @@ -815,7 +815,7 @@ struct iscsi_stats {
>> * up to ISCSI_STATS_CUSTOM_MAX
>> */
>> uint32_t custom_length;
>> -struct iscsi_stats_custom custom[0]
>> +struct iscsi_stats_custom custom[]
>> __attribute__ ((aligned (sizeof(uint64_t;
>> };
>>
>> @@ -946,7 +946,7 @@ struct iscsi_offload_host_stats {
>> * up to ISCSI_HOST_STATS_CUSTOM_MAX
>> */
>> uint32_t custom_length;
>> -struct iscsi_host_stats_custom custom[0]
>> +struct iscsi_host_stats_custom custom[]
>> __aligned(sizeof(uint64_t));
>> };
>>
>> diff --git a/include/scsi/scsi_bsg_iscsi.h b/include/scsi/scsi_bsg_iscsi.h
>> index fa0c820a1663..6b8128005af8 100644
>> --- a/include/scsi/scsi_bsg_iscsi.h
>> +++ b/include/scsi/scsi_bsg_iscsi.h
>> @@ -52,7 +52,7 @@ struct iscsi_bsg_host_vendor {
>> uint64_t vendor_id;
>>
>> /* start of vendor command area */
>> -uint32_t vendor_cmd[0];
>> +uint32_t vendor_cmd[];
>> };
>>
>> /* Response:
>> diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
>> index f8312a3e5b42..4dc158cf09b8 100644
>> --- a/include/scsi/scsi_device.h
>> +++ b/include/scsi/scsi_device.h
>> @@ -231,7 +231,7 @@ struct scsi_device {
>> struct mutexstate_mutex;
>> enum scsi_device_state sdev_state;
>> struct task_struct *quiesced_by;
>> -unsigned long sdev_data[0];
>> +unsigned long sdev_data[];
>> } __attribute__((aligned(sizeof(unsigned long;
>>
>> #define to_scsi_device(d) \
>> @@ -315,7 +315,7 @@ struct scsi_target {
>> charscsi_level;
>> enum scsi_target_state state;
>> void*hostdata; /* available to low-level driver */
>> -unsigned long starget_data[0]; /* for the transport */
>> +unsigned long starget_data[]; /* for the transport */
>> /* starget_data must be the last element */
>> } __attribute__((aligned(sizeof(unsigned long;
>>
>> diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
>> index 7a97fb8104cf..e6811ea8f984 100644
>> --- a/include/scsi/scsi_host.h
>> +++ b/include/scsi/scsi_host.h
>> @@ -682,7 +682,7 @@ struct Scsi_Host {
>> * and also because some compilers (m68k) don't automatically force
>> * alignment to a long boundary.
>> */
>> -
Re: [PATCH] scsi: Replace zero-length array with flexible-array member
Reviewed-by: Satish Kharat
From: Gustavo A. R. Silva
Sent: Monday, February 24, 2020 8:42 AM
To: Lee Duncan ; Satish Kharat (satishkh)
; Sesidhar Baddela (sebaddel) ; Karan
Tilak Kumar (kartilak) ; James E.J. Bottomley
; Martin K. Petersen ; Brian
King ; Intel SCU Linux support ;
Artur Paszkiewicz ; Sathya Prakash
; Chaitra P B ;
Suganath Prabu Subramani ; Chris Leech
; Bart Van Assche
Cc: linux-s...@vger.kernel.org ;
linux-ker...@vger.kernel.org ;
mpt-fusionlinux@broadcom.com ;
open-iscsi@googlegroups.com ;
linux-r...@vger.kernel.org
Subject: Re: [PATCH] scsi: Replace zero-length array with flexible-array member
On 2/24/20 10:30, Lee Duncan wrote:
> On 2/24/20 8:14 AM, Gustavo A. R. Silva wrote:
>> 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 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
>>
>> Signed-off-by: Gustavo A. R. Silva
>> ---
>> ...
>> diff --git a/include/scsi/iscsi_if.h b/include/scsi/iscsi_if.h
>> index 92b11c7e0b4f..b0e240b10bf9 100644
>> --- a/include/scsi/iscsi_if.h
>> +++ b/include/scsi/iscsi_if.h
>> @@ -311,7 +311,7 @@ enum iscsi_param_type {
>> struct iscsi_param_info {
>> uint32_t len; /* Actual length of the param value */
>> uint16_t param; /* iscsi param */
>> -uint8_t value[0]; /* length sized value follows */
>> +uint8_t value[];/* length sized value follows */
>> } __packed;
>>
>> struct iscsi_iface_param_info {
>> @@ -320,7 +320,7 @@ struct iscsi_iface_param_info {
>> uint16_t param; /* iscsi param value */
>> uint8_t iface_type; /* IPv4 or IPv6 */
>> uint8_t param_type; /* iscsi_param_type */
>> -uint8_t value[0]; /* length sized value follows */
>> +uint8_t value[];/* length sized value follows */
>> } __packed;
>>
>> /*
>> @@ -697,7 +697,7 @@ enum iscsi_flashnode_param {
>> struct iscsi_flashnode_param_info {
>> uint32_t len; /* Actual length of the param */
>> uint16_t param; /* iscsi param value */
>> -uint8_t value[0]; /* length sized value follows */
>> +uint8_t value[];/* length sized value follows */
>> } __packed;
>>
>> enum iscsi_discovery_parent_type {
>> @@ -815,7 +815,7 @@ struct iscsi_stats {
>>* up to ISCSI_STATS_CUSTOM_MAX
>>*/
>> uint32_t custom_length;
>> -struct iscsi_stats_custom custom[0]
>> +struct iscsi_stats_custom custom[]
>> __attribute__ ((aligned (sizeof(uint64_t;
>> };
>>
>> @@ -946,7 +946,7 @@ struct iscsi_offload_host_stats {
>>* up to ISCSI_HOST_STATS_CUSTOM_MAX
>>*/
>> uint32_t custom_length;
>> -struct iscsi_host_stats_custom custom[0]
>> +struct iscsi_host_stats_custom custom[]
>> __aligned(sizeof(uint64_t));
>> };
>>
>> diff --git a/include/scsi/scsi_bsg_iscsi.h b/include/scsi/scsi_bsg_iscsi.h
>> index fa0c820a1663..6b8128005af8 100644
>> --- a/include/scsi/scsi_bsg_iscsi.h
>> +++ b/include/scsi/scsi_bsg_iscsi.h
>> @@ -52,7 +52,7 @@ struct iscsi_bsg_host_vendor {
>> uint64_t vendor_id;
>>
>> /* start of vendor command area */
>> -uint32_t vendor_cmd[0];
>> +uint32_t vendor_cmd[];
>> };
>>
>> /* Response:
>> diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
>> index f8312a3e5b42..4dc158cf09b8 100644
>> --- a/include/scsi/scsi_device.h
>> +++ b/include/scsi/scsi_device.h
>> @@ -231,7 +231,7 @@ struct scsi_device {
>> struct mutexstate_mutex;
>> enum scsi_device_state sdev_state;
>> struct task_struct *quiesced_by;
>> -unsigned long sdev_data[0];
>> +unsigned long sdev_data[];
>> } __attribute__((aligned(sizeof(unsigned long;
>>
>> #define to_scsi_device(d) \
>> @@ -315,7 +315,7 @@ struct scsi_target {
>> charscsi_level;
>> enum scsi_target_state state;
>> void
Tagging version 2.1.1 of open-iscsi/open-iscsi
Hi All: Just a heads up (for those that don't hang out on github) that I'm tagging version 2.1.1 of open-iscsi today, if there are no objections. -- You received this message because you are subscribed to the Google Groups "open-iscsi" group. To unsubscribe from this group and stop receiving emails from it, send an email to open-iscsi+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/open-iscsi/54aefe03-21e2-4b91-8593-7d178bbf50c7%40googlegroups.com.
