2020-06-16 09:52:29

by Marco Elver

[permalink] [raw]
Subject: [PATCH] torture: Pass --kmake-arg to all make invocations

We need to pass the arguments provided to --kmake-arg to all make
invocations. In particular, the make invocations generating the configs
need to see the final make arguments, e.g. if config variables depend on
particular variables that are passed to make.

For example, when using '--kcsan --kmake-arg CC=clang-11', we would lose
CONFIG_KCSAN=y due to 'make oldconfig' not seeing that we want to use a
compiler that supports KCSAN.

Signed-off-by: Marco Elver <[email protected]>
---
tools/testing/selftests/rcutorture/bin/configinit.sh | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/rcutorture/bin/configinit.sh b/tools/testing/selftests/rcutorture/bin/configinit.sh
index 93e80a42249a..d6e5ce084b1c 100755
--- a/tools/testing/selftests/rcutorture/bin/configinit.sh
+++ b/tools/testing/selftests/rcutorture/bin/configinit.sh
@@ -32,11 +32,11 @@ if test -z "$TORTURE_TRUST_MAKE"
then
make clean > $resdir/Make.clean 2>&1
fi
-make $TORTURE_DEFCONFIG > $resdir/Make.defconfig.out 2>&1
+make $TORTURE_KMAKE_ARG $TORTURE_DEFCONFIG > $resdir/Make.defconfig.out 2>&1
mv .config .config.sav
sh $T/upd.sh < .config.sav > .config
cp .config .config.new
-yes '' | make oldconfig > $resdir/Make.oldconfig.out 2> $resdir/Make.oldconfig.err
+yes '' | make $TORTURE_KMAKE_ARG oldconfig > $resdir/Make.oldconfig.out 2> $resdir/Make.oldconfig.err

# verify new config matches specification.
configcheck.sh .config $c
--
2.27.0.290.gba653c62da-goog


2020-06-16 16:07:44

by Paul E. McKenney

[permalink] [raw]
Subject: Re: [PATCH] torture: Pass --kmake-arg to all make invocations

On Tue, Jun 16, 2020 at 11:49:24AM +0200, Marco Elver wrote:
> We need to pass the arguments provided to --kmake-arg to all make
> invocations. In particular, the make invocations generating the configs
> need to see the final make arguments, e.g. if config variables depend on
> particular variables that are passed to make.
>
> For example, when using '--kcsan --kmake-arg CC=clang-11', we would lose
> CONFIG_KCSAN=y due to 'make oldconfig' not seeing that we want to use a
> compiler that supports KCSAN.
>
> Signed-off-by: Marco Elver <[email protected]>

Queued and pushed, thank you!

Would the following patch make sense, at least until such time
as some other compiler supports KCSAN?

Thanx, Paul

------------------------------------------------------------------------

commit 88bcaa730b6d40ddf69b09ed6f0a14803d087d99
Author: Paul E. McKenney <[email protected]>
Date: Tue Jun 16 09:02:34 2020 -0700

torture: Make --kcsan default to using Clang 11

Currently, Clang 11 is the only compiler that can support KCSAN.
Therefore, as a convenience to the KCSAN user, this commit causes
--kcsan to specify Clang 11 unless a "CC=" argument was already
specified via the --kmake-arg argument.

Signed-off-by: Paul E. McKenney <[email protected]>

diff --git a/tools/testing/selftests/rcutorture/bin/kvm.sh b/tools/testing/selftests/rcutorture/bin/kvm.sh
index 446f680..f8c6cfa 100755
--- a/tools/testing/selftests/rcutorture/bin/kvm.sh
+++ b/tools/testing/selftests/rcutorture/bin/kvm.sh
@@ -34,6 +34,7 @@ TORTURE_KCONFIG_ARG=""
TORTURE_KCONFIG_KASAN_ARG=""
TORTURE_KCONFIG_KCSAN_ARG=""
TORTURE_KMAKE_ARG=""
+TORTURE_KMAKE_KCSAN_ARG=""
TORTURE_QEMU_MEM=512
TORTURE_SHUTDOWN_GRACE=180
TORTURE_SUITE=rcu
@@ -144,6 +145,7 @@ do
;;
--kcsan)
TORTURE_KCONFIG_KCSAN_ARG="CONFIG_DEBUG_INFO=y CONFIG_KCSAN=y CONFIG_KCSAN_ASSUME_PLAIN_WRITES_ATOMIC=n CONFIG_KCSAN_REPORT_VALUE_CHANGE_ONLY=n CONFIG_KCSAN_REPORT_ONCE_IN_MS=100000 CONFIG_KCSAN_VERBOSE=y CONFIG_KCSAN_INTERRUPT_WATCHER=y"; export TORTURE_KCONFIG_KCSAN_ARG
+ TORTURE_KMAKE_KCSAN_ARG="CC=clang-11"
;;
--kmake-arg)
checkarg --kmake-arg "(kernel make arguments)" $# "$2" '.*' '^error$'
@@ -214,6 +216,11 @@ else
exit 1
fi

+if test -n "$TORTURE_KMAKE_KCSAN_ARG" && ! echo "$TORTURE_KMAKE_ARG" | grep -q 'CC='
+then
+ TORTURE_KMAKE_ARG="$TORTURE_KMAKE_ARG $TORTURE_KMAKE_KCSAN_ARG"
+fi
+
CONFIGFRAG=${KVM}/configs/${TORTURE_SUITE}; export CONFIGFRAG

defaultconfigs="`tr '\012' ' ' < $CONFIGFRAG/CFLIST`"

2020-06-16 16:46:46

by Marco Elver

[permalink] [raw]
Subject: Re: [PATCH] torture: Pass --kmake-arg to all make invocations

On Tue, Jun 16 2020 at 09:05AM -0700, Paul E. McKenney wrote:

> On Tue, Jun 16, 2020 at 11:49:24AM +0200, Marco Elver wrote:
> > We need to pass the arguments provided to --kmake-arg to all make
> > invocations. In particular, the make invocations generating the configs
> > need to see the final make arguments, e.g. if config variables depend on
> > particular variables that are passed to make.
> >
> > For example, when using '--kcsan --kmake-arg CC=clang-11', we would lose
> > CONFIG_KCSAN=y due to 'make oldconfig' not seeing that we want to use a
> > compiler that supports KCSAN.
> >
> > Signed-off-by: Marco Elver <[email protected]>
>
> Queued and pushed, thank you!
>
> Would the following patch make sense, at least until such time
> as some other compiler supports KCSAN?
>
> Thanx, Paul
>
> ------------------------------------------------------------------------
>
> commit 88bcaa730b6d40ddf69b09ed6f0a14803d087d99
> Author: Paul E. McKenney <[email protected]>
> Date: Tue Jun 16 09:02:34 2020 -0700
>
> torture: Make --kcsan default to using Clang 11
>
> Currently, Clang 11 is the only compiler that can support KCSAN.
> Therefore, as a convenience to the KCSAN user, this commit causes
> --kcsan to specify Clang 11 unless a "CC=" argument was already
> specified via the --kmake-arg argument.

As soon as more compilers support KCSAN (e.g. clang-12, etc...) we run
the risk of actually inconveniencing ourselves more because then we
really need to say '--kmake-arg CC=clang-1X' to not use the old
compiler. Or revert this in time.

My command-line looks more like this right now:

kvm.sh ... --kmake-arg "CC="${HOME}/local/<gcc-or-clang>-11.kcsan/local/bin/<gcc-or-clang>" ...

I think the safer alternative would be to error if CONFIG_KCSAN=y is not
in the config, and simply suggest "Did you forget to switch your
compiler with '--kmake-arg CC=<cc-that-supports-kcsan>'?" (of course, a
'gcc' in $PATH that supports KCSAN would also be fine -- see below).
Eventually, when the default compilers support KCSAN, this will resolve
itself gracefully.

Also, I'm going to send a series later this week to re-enable GCC
support. ;-)

Thanks,
-- Marco

2020-06-16 17:44:44

by Paul E. McKenney

[permalink] [raw]
Subject: Re: [PATCH] torture: Pass --kmake-arg to all make invocations

On Tue, Jun 16, 2020 at 06:42:02PM +0200, Marco Elver wrote:
> On Tue, Jun 16 2020 at 09:05AM -0700, Paul E. McKenney wrote:
>
> > On Tue, Jun 16, 2020 at 11:49:24AM +0200, Marco Elver wrote:
> > > We need to pass the arguments provided to --kmake-arg to all make
> > > invocations. In particular, the make invocations generating the configs
> > > need to see the final make arguments, e.g. if config variables depend on
> > > particular variables that are passed to make.
> > >
> > > For example, when using '--kcsan --kmake-arg CC=clang-11', we would lose
> > > CONFIG_KCSAN=y due to 'make oldconfig' not seeing that we want to use a
> > > compiler that supports KCSAN.
> > >
> > > Signed-off-by: Marco Elver <[email protected]>
> >
> > Queued and pushed, thank you!
> >
> > Would the following patch make sense, at least until such time
> > as some other compiler supports KCSAN?
> >
> > Thanx, Paul
> >
> > ------------------------------------------------------------------------
> >
> > commit 88bcaa730b6d40ddf69b09ed6f0a14803d087d99
> > Author: Paul E. McKenney <[email protected]>
> > Date: Tue Jun 16 09:02:34 2020 -0700
> >
> > torture: Make --kcsan default to using Clang 11
> >
> > Currently, Clang 11 is the only compiler that can support KCSAN.
> > Therefore, as a convenience to the KCSAN user, this commit causes
> > --kcsan to specify Clang 11 unless a "CC=" argument was already
> > specified via the --kmake-arg argument.
>
> As soon as more compilers support KCSAN (e.g. clang-12, etc...) we run
> the risk of actually inconveniencing ourselves more because then we
> really need to say '--kmake-arg CC=clang-1X' to not use the old
> compiler. Or revert this in time.
>
> My command-line looks more like this right now:
>
> kvm.sh ... --kmake-arg "CC="${HOME}/local/<gcc-or-clang>-11.kcsan/local/bin/<gcc-or-clang>" ...
>
> I think the safer alternative would be to error if CONFIG_KCSAN=y is not
> in the config, and simply suggest "Did you forget to switch your
> compiler with '--kmake-arg CC=<cc-that-supports-kcsan>'?" (of course, a
> 'gcc' in $PATH that supports KCSAN would also be fine -- see below).
> Eventually, when the default compilers support KCSAN, this will resolve
> itself gracefully.
>
> Also, I'm going to send a series later this week to re-enable GCC
> support. ;-)

OK, sounds like I should leave well enough alone, then. ;-)

In its current state, specifying "--kcsan" without a KCSAN-capable
compiler does get you this:

:CONFIG_KCSAN=y: improperly set
:CONFIG_KCSAN_REPORT_ONCE_IN_MS=100000: improperly set
:CONFIG_KCSAN_VERBOSE=y: improperly set
:CONFIG_KCSAN_INTERRUPT_WATCHER=y: improperly set
Clean KCSAN run in /home/git/linux-rcu/tools/testing/selftests/rcutorture/res/2020.06.16-09.53.16

Which admittedly is a bit obtuse, especially that last line. So how
about the following patch, which instead results in this?

:CONFIG_KCSAN=y: improperly set
:CONFIG_KCSAN_REPORT_ONCE_IN_MS=100000: improperly set
:CONFIG_KCSAN_VERBOSE=y: improperly set
:CONFIG_KCSAN_INTERRUPT_WATCHER=y: improperly set
Did you forget to switch your compiler with --kmake-arg CC=<cc-that-supports-kcsan>?

Thanx, Paul

------------------------------------------------------------------------

commit f571795b1146007407851675a258b6685ea2d589
Author: Paul E. McKenney <[email protected]>
Date: Tue Jun 16 10:38:57 2020 -0700

torture: Improve diagnostic for KCSAN-incapable compilers

Using --kcsan when the compiler does not support KCSAN results in this:

:CONFIG_KCSAN=y: improperly set
:CONFIG_KCSAN_REPORT_ONCE_IN_MS=100000: improperly set
:CONFIG_KCSAN_VERBOSE=y: improperly set
:CONFIG_KCSAN_INTERRUPT_WATCHER=y: improperly set
Clean KCSAN run in /home/git/linux-rcu/tools/testing/selftests/rcutorture/res/2020.06.16-09.53.16

This is a bit obtuse, so this commit adds checks resulting in this:

:CONFIG_KCSAN=y: improperly set
:CONFIG_KCSAN_REPORT_ONCE_IN_MS=100000: improperly set
:CONFIG_KCSAN_VERBOSE=y: improperly set
:CONFIG_KCSAN_INTERRUPT_WATCHER=y: improperly set
Did you forget to switch your compiler with --kmake-arg CC=<cc-that-supports-kcsan>?

Suggested-by: Marco Elver <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>

diff --git a/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh b/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh
index 357899c..837643a 100755
--- a/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh
+++ b/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh
@@ -44,7 +44,8 @@ do
then
echo QEMU killed
fi
- configcheck.sh $i/.config $i/ConfigFragment
+ configcheck.sh $i/.config $i/ConfigFragment > $T 2>&1
+ cat $T
if test -r $i/Make.oldconfig.err
then
cat $i/Make.oldconfig.err
@@ -73,7 +74,10 @@ do
done
if test -f "$rd/kcsan.sum"
then
- if test -s "$rd/kcsan.sum"
+ if grep -q CONFIG_KCSAN=y $T
+ then
+ echo Did you forget to switch your compiler with '--kmake-arg CC=<cc-that-supports-kcsan>'?
+ elif test -s "$rd/kcsan.sum"
then
echo KCSAN summary in $rd/kcsan.sum
else

2020-06-16 18:00:09

by Marco Elver

[permalink] [raw]
Subject: Re: [PATCH] torture: Pass --kmake-arg to all make invocations

On Tue, Jun 16 2020 at 10:42AM -0700, Paul E. McKenney wrote:
> On Tue, Jun 16, 2020 at 06:42:02PM +0200, Marco Elver wrote:
> > On Tue, Jun 16 2020 at 09:05AM -0700, Paul E. McKenney wrote:
> > > On Tue, Jun 16, 2020 at 11:49:24AM +0200, Marco Elver wrote:
> > > > We need to pass the arguments provided to --kmake-arg to all make
> > > > invocations. In particular, the make invocations generating the configs
> > > > need to see the final make arguments, e.g. if config variables depend on
> > > > particular variables that are passed to make.
> > > >
> > > > For example, when using '--kcsan --kmake-arg CC=clang-11', we would lose
> > > > CONFIG_KCSAN=y due to 'make oldconfig' not seeing that we want to use a
> > > > compiler that supports KCSAN.
> > > >
> > > > Signed-off-by: Marco Elver <[email protected]>
> > >
> > > Queued and pushed, thank you!
> > >
> > > Would the following patch make sense, at least until such time
> > > as some other compiler supports KCSAN?
> > >
> > > Thanx, Paul
> > >
> > > ------------------------------------------------------------------------
> > >
> > > commit 88bcaa730b6d40ddf69b09ed6f0a14803d087d99
> > > Author: Paul E. McKenney <[email protected]>
> > > Date: Tue Jun 16 09:02:34 2020 -0700
> > >
> > > torture: Make --kcsan default to using Clang 11
> > >
> > > Currently, Clang 11 is the only compiler that can support KCSAN.
> > > Therefore, as a convenience to the KCSAN user, this commit causes
> > > --kcsan to specify Clang 11 unless a "CC=" argument was already
> > > specified via the --kmake-arg argument.
> >
> > As soon as more compilers support KCSAN (e.g. clang-12, etc...) we run
> > the risk of actually inconveniencing ourselves more because then we
> > really need to say '--kmake-arg CC=clang-1X' to not use the old
> > compiler. Or revert this in time.
> >
> > My command-line looks more like this right now:
> >
> > kvm.sh ... --kmake-arg "CC="${HOME}/local/<gcc-or-clang>-11.kcsan/local/bin/<gcc-or-clang>" ...
> >
> > I think the safer alternative would be to error if CONFIG_KCSAN=y is not
> > in the config, and simply suggest "Did you forget to switch your
> > compiler with '--kmake-arg CC=<cc-that-supports-kcsan>'?" (of course, a
> > 'gcc' in $PATH that supports KCSAN would also be fine -- see below).
> > Eventually, when the default compilers support KCSAN, this will resolve
> > itself gracefully.
> >
> > Also, I'm going to send a series later this week to re-enable GCC
> > support. ;-)
>
> OK, sounds like I should leave well enough alone, then. ;-)
>
> In its current state, specifying "--kcsan" without a KCSAN-capable
> compiler does get you this:
>
> :CONFIG_KCSAN=y: improperly set
> :CONFIG_KCSAN_REPORT_ONCE_IN_MS=100000: improperly set
> :CONFIG_KCSAN_VERBOSE=y: improperly set
> :CONFIG_KCSAN_INTERRUPT_WATCHER=y: improperly set
> Clean KCSAN run in /home/git/linux-rcu/tools/testing/selftests/rcutorture/res/2020.06.16-09.53.16
>
> Which admittedly is a bit obtuse, especially that last line. So how
> about the following patch, which instead results in this?
>
> :CONFIG_KCSAN=y: improperly set
> :CONFIG_KCSAN_REPORT_ONCE_IN_MS=100000: improperly set
> :CONFIG_KCSAN_VERBOSE=y: improperly set

Noticed that CONFIG_KCSAN_VERBOSE=y warning still appears, because it
wants CONFIG_PROVE_LOCKING=y.

> :CONFIG_KCSAN_INTERRUPT_WATCHER=y: improperly set
> Did you forget to switch your compiler with --kmake-arg CC=<cc-that-supports-kcsan>?

Sounds good, with another suggestion below, but otherwise

Acked-by: Marco Elver <[email protected]>

Thanks,
-- Marco

> Thanx, Paul
>
> ------------------------------------------------------------------------
>
> commit f571795b1146007407851675a258b6685ea2d589
> Author: Paul E. McKenney <[email protected]>
> Date: Tue Jun 16 10:38:57 2020 -0700
>
> torture: Improve diagnostic for KCSAN-incapable compilers
>
> Using --kcsan when the compiler does not support KCSAN results in this:
>
> :CONFIG_KCSAN=y: improperly set
> :CONFIG_KCSAN_REPORT_ONCE_IN_MS=100000: improperly set
> :CONFIG_KCSAN_VERBOSE=y: improperly set
> :CONFIG_KCSAN_INTERRUPT_WATCHER=y: improperly set
> Clean KCSAN run in /home/git/linux-rcu/tools/testing/selftests/rcutorture/res/2020.06.16-09.53.16
>
> This is a bit obtuse, so this commit adds checks resulting in this:
>
> :CONFIG_KCSAN=y: improperly set
> :CONFIG_KCSAN_REPORT_ONCE_IN_MS=100000: improperly set
> :CONFIG_KCSAN_VERBOSE=y: improperly set
> :CONFIG_KCSAN_INTERRUPT_WATCHER=y: improperly set
> Did you forget to switch your compiler with --kmake-arg CC=<cc-that-supports-kcsan>?
>
> Suggested-by: Marco Elver <[email protected]>
> Signed-off-by: Paul E. McKenney <[email protected]>
>
> diff --git a/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh b/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh
> index 357899c..837643a 100755
> --- a/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh
> +++ b/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh
> @@ -44,7 +44,8 @@ do
> then
> echo QEMU killed
> fi
> - configcheck.sh $i/.config $i/ConfigFragment
> + configcheck.sh $i/.config $i/ConfigFragment > $T 2>&1
> + cat $T
> if test -r $i/Make.oldconfig.err
> then
> cat $i/Make.oldconfig.err
> @@ -73,7 +74,10 @@ do
> done
> if test -f "$rd/kcsan.sum"
> then
> - if test -s "$rd/kcsan.sum"
> + if grep -q CONFIG_KCSAN=y $T
> + then

For completeness, could add this above:

echo "Compiler or architecture does not support KCSAN!"

Because we might also be on an unsupported architecture.

> + echo Did you forget to switch your compiler with '--kmake-arg CC=<cc-that-supports-kcsan>'?
> + elif test -s "$rd/kcsan.sum"
> then
> echo KCSAN summary in $rd/kcsan.sum
> else

2020-06-16 18:10:33

by Paul E. McKenney

[permalink] [raw]
Subject: Re: [PATCH] torture: Pass --kmake-arg to all make invocations

On Tue, Jun 16, 2020 at 07:57:20PM +0200, Marco Elver wrote:
> On Tue, Jun 16 2020 at 10:42AM -0700, Paul E. McKenney wrote:
> > On Tue, Jun 16, 2020 at 06:42:02PM +0200, Marco Elver wrote:
> > > On Tue, Jun 16 2020 at 09:05AM -0700, Paul E. McKenney wrote:
> > > > On Tue, Jun 16, 2020 at 11:49:24AM +0200, Marco Elver wrote:
> > > > > We need to pass the arguments provided to --kmake-arg to all make
> > > > > invocations. In particular, the make invocations generating the configs
> > > > > need to see the final make arguments, e.g. if config variables depend on
> > > > > particular variables that are passed to make.
> > > > >
> > > > > For example, when using '--kcsan --kmake-arg CC=clang-11', we would lose
> > > > > CONFIG_KCSAN=y due to 'make oldconfig' not seeing that we want to use a
> > > > > compiler that supports KCSAN.
> > > > >
> > > > > Signed-off-by: Marco Elver <[email protected]>
> > > >
> > > > Queued and pushed, thank you!
> > > >
> > > > Would the following patch make sense, at least until such time
> > > > as some other compiler supports KCSAN?
> > > >
> > > > Thanx, Paul
> > > >
> > > > ------------------------------------------------------------------------
> > > >
> > > > commit 88bcaa730b6d40ddf69b09ed6f0a14803d087d99
> > > > Author: Paul E. McKenney <[email protected]>
> > > > Date: Tue Jun 16 09:02:34 2020 -0700
> > > >
> > > > torture: Make --kcsan default to using Clang 11
> > > >
> > > > Currently, Clang 11 is the only compiler that can support KCSAN.
> > > > Therefore, as a convenience to the KCSAN user, this commit causes
> > > > --kcsan to specify Clang 11 unless a "CC=" argument was already
> > > > specified via the --kmake-arg argument.
> > >
> > > As soon as more compilers support KCSAN (e.g. clang-12, etc...) we run
> > > the risk of actually inconveniencing ourselves more because then we
> > > really need to say '--kmake-arg CC=clang-1X' to not use the old
> > > compiler. Or revert this in time.
> > >
> > > My command-line looks more like this right now:
> > >
> > > kvm.sh ... --kmake-arg "CC="${HOME}/local/<gcc-or-clang>-11.kcsan/local/bin/<gcc-or-clang>" ...
> > >
> > > I think the safer alternative would be to error if CONFIG_KCSAN=y is not
> > > in the config, and simply suggest "Did you forget to switch your
> > > compiler with '--kmake-arg CC=<cc-that-supports-kcsan>'?" (of course, a
> > > 'gcc' in $PATH that supports KCSAN would also be fine -- see below).
> > > Eventually, when the default compilers support KCSAN, this will resolve
> > > itself gracefully.
> > >
> > > Also, I'm going to send a series later this week to re-enable GCC
> > > support. ;-)
> >
> > OK, sounds like I should leave well enough alone, then. ;-)
> >
> > In its current state, specifying "--kcsan" without a KCSAN-capable
> > compiler does get you this:
> >
> > :CONFIG_KCSAN=y: improperly set
> > :CONFIG_KCSAN_REPORT_ONCE_IN_MS=100000: improperly set
> > :CONFIG_KCSAN_VERBOSE=y: improperly set
> > :CONFIG_KCSAN_INTERRUPT_WATCHER=y: improperly set
> > Clean KCSAN run in /home/git/linux-rcu/tools/testing/selftests/rcutorture/res/2020.06.16-09.53.16
> >
> > Which admittedly is a bit obtuse, especially that last line. So how
> > about the following patch, which instead results in this?
> >
> > :CONFIG_KCSAN=y: improperly set
> > :CONFIG_KCSAN_REPORT_ONCE_IN_MS=100000: improperly set
> > :CONFIG_KCSAN_VERBOSE=y: improperly set
>
> Noticed that CONFIG_KCSAN_VERBOSE=y warning still appears, because it
> wants CONFIG_PROVE_LOCKING=y.
>
> > :CONFIG_KCSAN_INTERRUPT_WATCHER=y: improperly set
> > Did you forget to switch your compiler with --kmake-arg CC=<cc-that-supports-kcsan>?
>
> Sounds good, with another suggestion below, but otherwise
>
> Acked-by: Marco Elver <[email protected]>

Applied and updated as suggested below, so that the output now looks
like this:

:CONFIG_KCSAN=y: improperly set
:CONFIG_KCSAN_REPORT_ONCE_IN_MS=100000: improperly set
:CONFIG_KCSAN_VERBOSE=y: improperly set
:CONFIG_KCSAN_INTERRUPT_WATCHER=y: improperly set
Compiler or architecture does not support KCSAN!
Did you forget to switch your compiler with --kmake-arg CC=<cc-that-supports-kcsan>?

And agreed, much better!

Thanx, Paul

> Thanks,
> -- Marco
>
> > Thanx, Paul
> >
> > ------------------------------------------------------------------------
> >
> > commit f571795b1146007407851675a258b6685ea2d589
> > Author: Paul E. McKenney <[email protected]>
> > Date: Tue Jun 16 10:38:57 2020 -0700
> >
> > torture: Improve diagnostic for KCSAN-incapable compilers
> >
> > Using --kcsan when the compiler does not support KCSAN results in this:
> >
> > :CONFIG_KCSAN=y: improperly set
> > :CONFIG_KCSAN_REPORT_ONCE_IN_MS=100000: improperly set
> > :CONFIG_KCSAN_VERBOSE=y: improperly set
> > :CONFIG_KCSAN_INTERRUPT_WATCHER=y: improperly set
> > Clean KCSAN run in /home/git/linux-rcu/tools/testing/selftests/rcutorture/res/2020.06.16-09.53.16
> >
> > This is a bit obtuse, so this commit adds checks resulting in this:
> >
> > :CONFIG_KCSAN=y: improperly set
> > :CONFIG_KCSAN_REPORT_ONCE_IN_MS=100000: improperly set
> > :CONFIG_KCSAN_VERBOSE=y: improperly set
> > :CONFIG_KCSAN_INTERRUPT_WATCHER=y: improperly set
> > Did you forget to switch your compiler with --kmake-arg CC=<cc-that-supports-kcsan>?
> >
> > Suggested-by: Marco Elver <[email protected]>
> > Signed-off-by: Paul E. McKenney <[email protected]>
> >
> > diff --git a/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh b/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh
> > index 357899c..837643a 100755
> > --- a/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh
> > +++ b/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh
> > @@ -44,7 +44,8 @@ do
> > then
> > echo QEMU killed
> > fi
> > - configcheck.sh $i/.config $i/ConfigFragment
> > + configcheck.sh $i/.config $i/ConfigFragment > $T 2>&1
> > + cat $T
> > if test -r $i/Make.oldconfig.err
> > then
> > cat $i/Make.oldconfig.err
> > @@ -73,7 +74,10 @@ do
> > done
> > if test -f "$rd/kcsan.sum"
> > then
> > - if test -s "$rd/kcsan.sum"
> > + if grep -q CONFIG_KCSAN=y $T
> > + then
>
> For completeness, could add this above:
>
> echo "Compiler or architecture does not support KCSAN!"
>
> Because we might also be on an unsupported architecture.
>
> > + echo Did you forget to switch your compiler with '--kmake-arg CC=<cc-that-supports-kcsan>'?
> > + elif test -s "$rd/kcsan.sum"
> > then
> > echo KCSAN summary in $rd/kcsan.sum
> > else