* [PATCH] media: gspca/gl860-mi1320: avoid -Wstring-concatenation warning
@ 2021-09-27 12:20 Arnd Bergmann
2021-10-04 10:55 ` Hans Verkuil
0 siblings, 1 reply; 4+ messages in thread
From: Arnd Bergmann @ 2021-09-27 12:20 UTC (permalink / raw)
To: Olivier Lorin, Hans Verkuil, Mauro Carvalho Chehab,
Nathan Chancellor, Nick Desaulniers
Cc: Arnd Bergmann, linux-media, linux-kernel, llvm
From: Arnd Bergmann <arnd@arndb.de>
Newer clang versions are suspicious of definitions that mix concatenated
strings with comma-separated arrays of strings, this has found real bugs
elsewhere, but this seems to be a false positive:
drivers/media/usb/gspca/gl860/gl860-mi1320.c:62:37: error: suspicious concatenation of string literals in an array initialization; did you mean to separate the elements with a comma? [-Werror,-Wstring-concatenation]
"\xd3\x02\xd4\x28\xd5\x01\xd0\x02" "\xd1\x18\xd2\xc1"
^
,
drivers/media/usb/gspca/gl860/gl860-mi1320.c:62:2: note: place parentheses around the string literal to silence warning
"\xd3\x02\xd4\x28\xd5\x01\xd0\x02" "\xd1\x18\xd2\xc1"
Use the extra parentheses as suggested in the warning message.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
drivers/media/usb/gspca/gl860/gl860-mi1320.c | 24 ++++++++++----------
1 file changed, 12 insertions(+), 12 deletions(-)
diff --git a/drivers/media/usb/gspca/gl860/gl860-mi1320.c b/drivers/media/usb/gspca/gl860/gl860-mi1320.c
index 0749fe13160f..1253eb145c99 100644
--- a/drivers/media/usb/gspca/gl860/gl860-mi1320.c
+++ b/drivers/media/usb/gspca/gl860/gl860-mi1320.c
@@ -49,44 +49,44 @@ static struct validx tbl_post_unset_alt[] = {
{0x0061, 0x0000}, {0x0068, 0x000d},
};
-static u8 *tbl_1280[] = {
+static u8 *tbl_1280[] = {(
"\x0d\x80\xf1\x08\x03\x04\xf1\x00" "\x04\x05\xf1\x02\x05\x00\xf1\xf1"
"\x06\x00\xf1\x0d\x20\x01\xf1\x00" "\x21\x84\xf1\x00\x0d\x00\xf1\x08"
"\xf0\x00\xf1\x01\x34\x00\xf1\x00" "\x9b\x43\xf1\x00\xa6\x05\xf1\x00"
"\xa9\x04\xf1\x00\xa1\x05\xf1\x00" "\xa4\x04\xf1\x00\xae\x0a\xf1\x08"
- ,
+ ), (
"\xf0\x00\xf1\x02\x3a\x05\xf1\xf1" "\x3c\x05\xf1\xf1\x59\x01\xf1\x47"
"\x5a\x01\xf1\x88\x5c\x0a\xf1\x06" "\x5d\x0e\xf1\x0a\x64\x5e\xf1\x1c"
"\xd2\x00\xf1\xcf\xcb\x00\xf1\x01"
- ,
+ ), (
"\xd3\x02\xd4\x28\xd5\x01\xd0\x02" "\xd1\x18\xd2\xc1"
-};
+)};
-static u8 *tbl_800[] = {
+static u8 *tbl_800[] = { (
"\x0d\x80\xf1\x08\x03\x03\xf1\xc0" "\x04\x05\xf1\x02\x05\x00\xf1\xf1"
"\x06\x00\xf1\x0d\x20\x01\xf1\x00" "\x21\x84\xf1\x00\x0d\x00\xf1\x08"
"\xf0\x00\xf1\x01\x34\x00\xf1\x00" "\x9b\x43\xf1\x00\xa6\x05\xf1\x00"
"\xa9\x03\xf1\xc0\xa1\x03\xf1\x20" "\xa4\x02\xf1\x5a\xae\x0a\xf1\x08"
- ,
+ ), (
"\xf0\x00\xf1\x02\x3a\x05\xf1\xf1" "\x3c\x05\xf1\xf1\x59\x01\xf1\x47"
"\x5a\x01\xf1\x88\x5c\x0a\xf1\x06" "\x5d\x0e\xf1\x0a\x64\x5e\xf1\x1c"
"\xd2\x00\xf1\xcf\xcb\x00\xf1\x01"
- ,
+ ), (
"\xd3\x02\xd4\x18\xd5\x21\xd0\x02" "\xd1\x10\xd2\x59"
-};
+)};
-static u8 *tbl_640[] = {
+static u8 *tbl_640[] = {(
"\x0d\x80\xf1\x08\x03\x04\xf1\x04" "\x04\x05\xf1\x02\x07\x01\xf1\x7c"
"\x08\x00\xf1\x0e\x21\x80\xf1\x00" "\x0d\x00\xf1\x08\xf0\x00\xf1\x01"
"\x34\x10\xf1\x10\x3a\x43\xf1\x00" "\xa6\x05\xf1\x02\xa9\x04\xf1\x04"
"\xa7\x02\xf1\x81\xaa\x01\xf1\xe2" "\xae\x0c\xf1\x09"
- ,
+ ), (
"\xf0\x00\xf1\x02\x39\x03\xf1\xfc" "\x3b\x04\xf1\x04\x57\x01\xf1\xb6"
"\x58\x02\xf1\x0d\x5c\x1f\xf1\x19" "\x5d\x24\xf1\x1e\x64\x5e\xf1\x1c"
"\xd2\x00\xf1\x00\xcb\x00\xf1\x01"
- ,
+ ), (
"\xd3\x02\xd4\x10\xd5\x81\xd0\x02" "\xd1\x08\xd2\xe1"
-};
+)};
static s32 tbl_sat[] = {0x25, 0x1d, 0x15, 0x0d, 0x05, 0x4d, 0x55, 0x5d, 0x2d};
static s32 tbl_bright[] = {0, 8, 0x10, 0x20, 0x30, 0x40, 0x50, 0x60, 0x70};
--
2.29.2
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] media: gspca/gl860-mi1320: avoid -Wstring-concatenation warning
2021-09-27 12:20 [PATCH] media: gspca/gl860-mi1320: avoid -Wstring-concatenation warning Arnd Bergmann
@ 2021-10-04 10:55 ` Hans Verkuil
2021-10-04 11:38 ` Arnd Bergmann
0 siblings, 1 reply; 4+ messages in thread
From: Hans Verkuil @ 2021-10-04 10:55 UTC (permalink / raw)
To: Arnd Bergmann, Olivier Lorin, Mauro Carvalho Chehab,
Nathan Chancellor, Nick Desaulniers
Cc: Arnd Bergmann, linux-media, linux-kernel, llvm
Hi Arnd,
On 27/09/2021 14:20, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
>
> Newer clang versions are suspicious of definitions that mix concatenated
> strings with comma-separated arrays of strings, this has found real bugs
> elsewhere, but this seems to be a false positive:
>
> drivers/media/usb/gspca/gl860/gl860-mi1320.c:62:37: error: suspicious concatenation of string literals in an array initialization; did you mean to separate the elements with a comma? [-Werror,-Wstring-concatenation]
> "\xd3\x02\xd4\x28\xd5\x01\xd0\x02" "\xd1\x18\xd2\xc1"
> ^
> ,
> drivers/media/usb/gspca/gl860/gl860-mi1320.c:62:2: note: place parentheses around the string literal to silence warning
> "\xd3\x02\xd4\x28\xd5\x01\xd0\x02" "\xd1\x18\xd2\xc1"
>
> Use the extra parentheses as suggested in the warning message.
I noticed that gl860-ov9655.c uses the same construct, doesn't that produce the
same warning?
Also, does clang only warn about 'static u8 *tbl[]' initializers, or also
for 'static u8 *tbl' initializers (i.e. not a pointer array) with the same
string concatenation?
I made a patch that replaces these ugly hex strings with compound initializers:
static u8 *tbl_640[] = {
(u8[]){
0x0d, 0x80, 0xf1, 0x08, 0x03, 0x04, 0xf1, 0x04,
0x04, 0x05, 0xf1, 0x02, 0x07, 0x01, 0xf1, 0x7c,
0x08, 0x00, 0xf1, 0x0e, 0x21, 0x80, 0xf1, 0x00,
0x0d, 0x00, 0xf1, 0x08, 0xf0, 0x00, 0xf1, 0x01,
0x34, 0x10, 0xf1, 0x10, 0x3a, 0x43, 0xf1, 0x00,
0xa6, 0x05, 0xf1, 0x02, 0xa9, 0x04, 0xf1, 0x04,
0xa7, 0x02, 0xf1, 0x81, 0xaa, 0x01, 0xf1, 0xe2,
0xae, 0x0c, 0xf1, 0x09
}, (u8[]){
0xf0, 0x00, 0xf1, 0x02, 0x39, 0x03, 0xf1, 0xfc,
0x3b, 0x04, 0xf1, 0x04, 0x57, 0x01, 0xf1, 0xb6,
0x58, 0x02, 0xf1, 0x0d, 0x5c, 0x1f, 0xf1, 0x19,
0x5d, 0x24, 0xf1, 0x1e, 0x64, 0x5e, 0xf1, 0x1c,
0xd2, 0x00, 0xf1, 0x00, 0xcb, 0x00, 0xf1, 0x01
}, (u8[]){
0xd3, 0x02, 0xd4, 0x10, 0xd5, 0x81, 0xd0, 0x02,
0xd1, 0x08, 0xd2, 0xe1
}
};
but it clang also warns about 'static u8 *tbl' multi-string initializers,
then it would make sense to replace all these hex-strings. It's rather
ugly.
Regards,
Hans
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> drivers/media/usb/gspca/gl860/gl860-mi1320.c | 24 ++++++++++----------
> 1 file changed, 12 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/media/usb/gspca/gl860/gl860-mi1320.c b/drivers/media/usb/gspca/gl860/gl860-mi1320.c
> index 0749fe13160f..1253eb145c99 100644
> --- a/drivers/media/usb/gspca/gl860/gl860-mi1320.c
> +++ b/drivers/media/usb/gspca/gl860/gl860-mi1320.c
> @@ -49,44 +49,44 @@ static struct validx tbl_post_unset_alt[] = {
> {0x0061, 0x0000}, {0x0068, 0x000d},
> };
>
> -static u8 *tbl_1280[] = {
> +static u8 *tbl_1280[] = {(
> "\x0d\x80\xf1\x08\x03\x04\xf1\x00" "\x04\x05\xf1\x02\x05\x00\xf1\xf1"
> "\x06\x00\xf1\x0d\x20\x01\xf1\x00" "\x21\x84\xf1\x00\x0d\x00\xf1\x08"
> "\xf0\x00\xf1\x01\x34\x00\xf1\x00" "\x9b\x43\xf1\x00\xa6\x05\xf1\x00"
> "\xa9\x04\xf1\x00\xa1\x05\xf1\x00" "\xa4\x04\xf1\x00\xae\x0a\xf1\x08"
> - ,
> + ), (
> "\xf0\x00\xf1\x02\x3a\x05\xf1\xf1" "\x3c\x05\xf1\xf1\x59\x01\xf1\x47"
> "\x5a\x01\xf1\x88\x5c\x0a\xf1\x06" "\x5d\x0e\xf1\x0a\x64\x5e\xf1\x1c"
> "\xd2\x00\xf1\xcf\xcb\x00\xf1\x01"
> - ,
> + ), (
> "\xd3\x02\xd4\x28\xd5\x01\xd0\x02" "\xd1\x18\xd2\xc1"
> -};
> +)};
>
> -static u8 *tbl_800[] = {
> +static u8 *tbl_800[] = { (
> "\x0d\x80\xf1\x08\x03\x03\xf1\xc0" "\x04\x05\xf1\x02\x05\x00\xf1\xf1"
> "\x06\x00\xf1\x0d\x20\x01\xf1\x00" "\x21\x84\xf1\x00\x0d\x00\xf1\x08"
> "\xf0\x00\xf1\x01\x34\x00\xf1\x00" "\x9b\x43\xf1\x00\xa6\x05\xf1\x00"
> "\xa9\x03\xf1\xc0\xa1\x03\xf1\x20" "\xa4\x02\xf1\x5a\xae\x0a\xf1\x08"
> - ,
> + ), (
> "\xf0\x00\xf1\x02\x3a\x05\xf1\xf1" "\x3c\x05\xf1\xf1\x59\x01\xf1\x47"
> "\x5a\x01\xf1\x88\x5c\x0a\xf1\x06" "\x5d\x0e\xf1\x0a\x64\x5e\xf1\x1c"
> "\xd2\x00\xf1\xcf\xcb\x00\xf1\x01"
> - ,
> + ), (
> "\xd3\x02\xd4\x18\xd5\x21\xd0\x02" "\xd1\x10\xd2\x59"
> -};
> +)};
>
> -static u8 *tbl_640[] = {
> +static u8 *tbl_640[] = {(
> "\x0d\x80\xf1\x08\x03\x04\xf1\x04" "\x04\x05\xf1\x02\x07\x01\xf1\x7c"
> "\x08\x00\xf1\x0e\x21\x80\xf1\x00" "\x0d\x00\xf1\x08\xf0\x00\xf1\x01"
> "\x34\x10\xf1\x10\x3a\x43\xf1\x00" "\xa6\x05\xf1\x02\xa9\x04\xf1\x04"
> "\xa7\x02\xf1\x81\xaa\x01\xf1\xe2" "\xae\x0c\xf1\x09"
> - ,
> + ), (
> "\xf0\x00\xf1\x02\x39\x03\xf1\xfc" "\x3b\x04\xf1\x04\x57\x01\xf1\xb6"
> "\x58\x02\xf1\x0d\x5c\x1f\xf1\x19" "\x5d\x24\xf1\x1e\x64\x5e\xf1\x1c"
> "\xd2\x00\xf1\x00\xcb\x00\xf1\x01"
> - ,
> + ), (
> "\xd3\x02\xd4\x10\xd5\x81\xd0\x02" "\xd1\x08\xd2\xe1"
> -};
> +)};
>
> static s32 tbl_sat[] = {0x25, 0x1d, 0x15, 0x0d, 0x05, 0x4d, 0x55, 0x5d, 0x2d};
> static s32 tbl_bright[] = {0, 8, 0x10, 0x20, 0x30, 0x40, 0x50, 0x60, 0x70};
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] media: gspca/gl860-mi1320: avoid -Wstring-concatenation warning
2021-10-04 10:55 ` Hans Verkuil
@ 2021-10-04 11:38 ` Arnd Bergmann
0 siblings, 0 replies; 4+ messages in thread
From: Arnd Bergmann @ 2021-10-04 11:38 UTC (permalink / raw)
To: Hans Verkuil
Cc: Olivier Lorin, Mauro Carvalho Chehab, Nathan Chancellor,
Nick Desaulniers, Arnd Bergmann, Linux Media Mailing List,
Linux Kernel Mailing List, llvm
On Mon, Oct 4, 2021 at 12:55 PM Hans Verkuil <hverkuil@xs4all.nl> wrote:
>
> Hi Arnd,
>
> On 27/09/2021 14:20, Arnd Bergmann wrote:
> > From: Arnd Bergmann <arnd@arndb.de>
> >
> > Newer clang versions are suspicious of definitions that mix concatenated
> > strings with comma-separated arrays of strings, this has found real bugs
> > elsewhere, but this seems to be a false positive:
> >
> > drivers/media/usb/gspca/gl860/gl860-mi1320.c:62:37: error: suspicious concatenation of string literals in an array initialization; did you mean to separate the elements with a comma? [-Werror,-Wstring-concatenation]
> > "\xd3\x02\xd4\x28\xd5\x01\xd0\x02" "\xd1\x18\xd2\xc1"
> > ^
> > ,
> > drivers/media/usb/gspca/gl860/gl860-mi1320.c:62:2: note: place parentheses around the string literal to silence warning
> > "\xd3\x02\xd4\x28\xd5\x01\xd0\x02" "\xd1\x18\xd2\xc1"
> >
> > Use the extra parentheses as suggested in the warning message.
>
> I noticed that gl860-ov9655.c uses the same construct, doesn't that produce the
> same warning?
Curiously, it does not. I tried reproducing this in godbolt.org,
see https://godbolt.org/z/W6K69qcz3
For some reason, clang only warns about some of those, and it appears to
depend on the ratio between string concatenations and array elements.
> Also, does clang only warn about 'static u8 *tbl[]' initializers, or also
> for 'static u8 *tbl' initializers (i.e. not a pointer array) with the same
> string concatenation?
When there is only one element rather than an array, it does not warn,
because it's not a mix of concatenation and array elements.
> I made a patch that replaces these ugly hex strings with compound initializers:
>
> static u8 *tbl_640[] = {
> (u8[]){
> 0x0d, 0x80, 0xf1, 0x08, 0x03, 0x04, 0xf1, 0x04,
> 0x04, 0x05, 0xf1, 0x02, 0x07, 0x01, 0xf1, 0x7c,
> 0x08, 0x00, 0xf1, 0x0e, 0x21, 0x80, 0xf1, 0x00,
> 0x0d, 0x00, 0xf1, 0x08, 0xf0, 0x00, 0xf1, 0x01,
> 0x34, 0x10, 0xf1, 0x10, 0x3a, 0x43, 0xf1, 0x00,
> 0xa6, 0x05, 0xf1, 0x02, 0xa9, 0x04, 0xf1, 0x04,
> 0xa7, 0x02, 0xf1, 0x81, 0xaa, 0x01, 0xf1, 0xe2,
> 0xae, 0x0c, 0xf1, 0x09
> }, (u8[]){
> 0xf0, 0x00, 0xf1, 0x02, 0x39, 0x03, 0xf1, 0xfc,
> 0x3b, 0x04, 0xf1, 0x04, 0x57, 0x01, 0xf1, 0xb6,
> 0x58, 0x02, 0xf1, 0x0d, 0x5c, 0x1f, 0xf1, 0x19,
> 0x5d, 0x24, 0xf1, 0x1e, 0x64, 0x5e, 0xf1, 0x1c,
> 0xd2, 0x00, 0xf1, 0x00, 0xcb, 0x00, 0xf1, 0x01
> }, (u8[]){
> 0xd3, 0x02, 0xd4, 0x10, 0xd5, 0x81, 0xd0, 0x02,
> 0xd1, 0x08, 0xd2, 0xe1
> }
> };
>
> but it clang also warns about 'static u8 *tbl' multi-string initializers,
> then it would make sense to replace all these hex-strings. It's rather
> ugly.
This seems fine.
Arnd
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] media: gspca/gl860-mi1320: avoid -Wstring-concatenation warning
@ 2021-10-04 11:38 ` Arnd Bergmann
0 siblings, 0 replies; 4+ messages in thread
From: Arnd Bergmann @ 2021-10-04 11:38 UTC (permalink / raw)
To: Hans Verkuil
Cc: Olivier Lorin, Mauro Carvalho Chehab, Nathan Chancellor,
Nick Desaulniers, Arnd Bergmann, Linux Media Mailing List,
Linux Kernel Mailing List, llvm
On Mon, Oct 4, 2021 at 12:55 PM Hans Verkuil <hverkuil@xs4all.nl> wrote:
>
> Hi Arnd,
>
> On 27/09/2021 14:20, Arnd Bergmann wrote:
> > From: Arnd Bergmann <arnd@arndb.de>
> >
> > Newer clang versions are suspicious of definitions that mix concatenated
> > strings with comma-separated arrays of strings, this has found real bugs
> > elsewhere, but this seems to be a false positive:
> >
> > drivers/media/usb/gspca/gl860/gl860-mi1320.c:62:37: error: suspicious concatenation of string literals in an array initialization; did you mean to separate the elements with a comma? [-Werror,-Wstring-concatenation]
> > "\xd3\x02\xd4\x28\xd5\x01\xd0\x02" "\xd1\x18\xd2\xc1"
> > ^
> > ,
> > drivers/media/usb/gspca/gl860/gl860-mi1320.c:62:2: note: place parentheses around the string literal to silence warning
> > "\xd3\x02\xd4\x28\xd5\x01\xd0\x02" "\xd1\x18\xd2\xc1"
> >
> > Use the extra parentheses as suggested in the warning message.
>
> I noticed that gl860-ov9655.c uses the same construct, doesn't that produce the
> same warning?
Curiously, it does not. I tried reproducing this in godbolt.org,
see https://godbolt.org/z/W6K69qcz3
For some reason, clang only warns about some of those, and it appears to
depend on the ratio between string concatenations and array elements.
> Also, does clang only warn about 'static u8 *tbl[]' initializers, or also
> for 'static u8 *tbl' initializers (i.e. not a pointer array) with the same
> string concatenation?
When there is only one element rather than an array, it does not warn,
because it's not a mix of concatenation and array elements.
> I made a patch that replaces these ugly hex strings with compound initializers:
>
> static u8 *tbl_640[] = {
> (u8[]){
> 0x0d, 0x80, 0xf1, 0x08, 0x03, 0x04, 0xf1, 0x04,
> 0x04, 0x05, 0xf1, 0x02, 0x07, 0x01, 0xf1, 0x7c,
> 0x08, 0x00, 0xf1, 0x0e, 0x21, 0x80, 0xf1, 0x00,
> 0x0d, 0x00, 0xf1, 0x08, 0xf0, 0x00, 0xf1, 0x01,
> 0x34, 0x10, 0xf1, 0x10, 0x3a, 0x43, 0xf1, 0x00,
> 0xa6, 0x05, 0xf1, 0x02, 0xa9, 0x04, 0xf1, 0x04,
> 0xa7, 0x02, 0xf1, 0x81, 0xaa, 0x01, 0xf1, 0xe2,
> 0xae, 0x0c, 0xf1, 0x09
> }, (u8[]){
> 0xf0, 0x00, 0xf1, 0x02, 0x39, 0x03, 0xf1, 0xfc,
> 0x3b, 0x04, 0xf1, 0x04, 0x57, 0x01, 0xf1, 0xb6,
> 0x58, 0x02, 0xf1, 0x0d, 0x5c, 0x1f, 0xf1, 0x19,
> 0x5d, 0x24, 0xf1, 0x1e, 0x64, 0x5e, 0xf1, 0x1c,
> 0xd2, 0x00, 0xf1, 0x00, 0xcb, 0x00, 0xf1, 0x01
> }, (u8[]){
> 0xd3, 0x02, 0xd4, 0x10, 0xd5, 0x81, 0xd0, 0x02,
> 0xd1, 0x08, 0xd2, 0xe1
> }
> };
>
> but it clang also warns about 'static u8 *tbl' multi-string initializers,
> then it would make sense to replace all these hex-strings. It's rather
> ugly.
This seems fine.
Arnd
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2021-10-04 11:38 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2021-09-27 12:20 [PATCH] media: gspca/gl860-mi1320: avoid -Wstring-concatenation warning Arnd Bergmann
2021-10-04 10:55 ` Hans Verkuil
2021-10-04 11:38 ` Arnd Bergmann
2021-10-04 11:38 ` Arnd Bergmann
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