[PATCH v2] selftests: livepatch: Test atomic replace against multiple modules

[PATCH v2] selftests: livepatch: Test atomic replace against multiple modules

[Marcos Paulo de Souza]

Adapt the current test-livepatch.sh script to account the number of
applied livepatches and ensure that an atomic replace livepatch disables
all previously applied livepatches.

Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com>
---
Changes since v1:
* Added checks in the existing test-livepatch.sh instead of creating a
  new test file. (Joe)
* Fixed issues reported by ShellCheck (Joe)
---
 .../testing/selftests/livepatch/test-livepatch.sh  | 46 ++++++++++++++++++++--
 1 file changed, 42 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/livepatch/test-livepatch.sh b/tools/testing/selftests/livepatch/test-livepatch.sh
index e3455a6b1158..d85405d18e54 100755
--- a/tools/testing/selftests/livepatch/test-livepatch.sh
+++ b/tools/testing/selftests/livepatch/test-livepatch.sh
@@ -107,9 +107,12 @@ livepatch: '$MOD_LIVEPATCH': unpatching complete
 
 # - load a livepatch that modifies the output from /proc/cmdline and
 #   verify correct behavior
-# - load an atomic replace livepatch and verify that only the second is active
-# - remove the first livepatch and verify that the atomic replace livepatch
-#   is still active
+# - load two addtional livepatches and check the number of livepatch modules
+#   applied
+# - load an atomic replace livepatch and check that the other three modules were
+#   disabled
+# - remove all livepatches besides the atomic replace one and verify that the
+#   atomic replace livepatch is still active
 # - remove the atomic replace livepatch and verify that none are active
 
 start_test "atomic replace livepatch"
@@ -119,12 +122,31 @@ load_lp $MOD_LIVEPATCH
 grep 'live patched' /proc/cmdline > /dev/kmsg
 grep 'live patched' /proc/meminfo > /dev/kmsg
 
+for mod in test_klp_syscall test_klp_callbacks_demo; do
+	load_lp $mod
+done
+
+mods=(/sys/kernel/livepatch/*)
+nmods=${#mods[@]}
+if [ "$nmods" -ne 3 ]; then
+	die "Expecting three modules listed, found $nmods"
+fi
+
 load_lp $MOD_REPLACE replace=1
 
 grep 'live patched' /proc/cmdline > /dev/kmsg
 grep 'live patched' /proc/meminfo > /dev/kmsg
 
-unload_lp $MOD_LIVEPATCH
+mods=(/sys/kernel/livepatch/*)
+nmods=${#mods[@]}
+if [ "$nmods" -ne 1 ]; then
+	die "Expecting only one moduled listed, found $nmods"
+fi
+
+# These modules were disabled by the atomic replace
+for mod in test_klp_callbacks_demo test_klp_syscall $MOD_LIVEPATCH; do
+	unload_lp "$mod"
+done
 
 grep 'live patched' /proc/cmdline > /dev/kmsg
 grep 'live patched' /proc/meminfo > /dev/kmsg
@@ -142,6 +164,20 @@ livepatch: '$MOD_LIVEPATCH': starting patching transition
 livepatch: '$MOD_LIVEPATCH': completing patching transition
 livepatch: '$MOD_LIVEPATCH': patching complete
 $MOD_LIVEPATCH: this has been live patched
+% insmod test_modules/test_klp_syscall.ko
+livepatch: enabling patch 'test_klp_syscall'
+livepatch: 'test_klp_syscall': initializing patching transition
+livepatch: 'test_klp_syscall': starting patching transition
+livepatch: 'test_klp_syscall': completing patching transition
+livepatch: 'test_klp_syscall': patching complete
+% insmod test_modules/test_klp_callbacks_demo.ko
+livepatch: enabling patch 'test_klp_callbacks_demo'
+livepatch: 'test_klp_callbacks_demo': initializing patching transition
+test_klp_callbacks_demo: pre_patch_callback: vmlinux
+livepatch: 'test_klp_callbacks_demo': starting patching transition
+livepatch: 'test_klp_callbacks_demo': completing patching transition
+test_klp_callbacks_demo: post_patch_callback: vmlinux
+livepatch: 'test_klp_callbacks_demo': patching complete
 % insmod test_modules/$MOD_REPLACE.ko replace=1
 livepatch: enabling patch '$MOD_REPLACE'
 livepatch: '$MOD_REPLACE': initializing patching transition
@@ -149,6 +185,8 @@ livepatch: '$MOD_REPLACE': starting patching transition
 livepatch: '$MOD_REPLACE': completing patching transition
 livepatch: '$MOD_REPLACE': patching complete
 $MOD_REPLACE: this has been live patched
+% rmmod test_klp_callbacks_demo
+% rmmod test_klp_syscall
 % rmmod $MOD_LIVEPATCH
 $MOD_REPLACE: this has been live patched
 % echo 0 > /sys/kernel/livepatch/$MOD_REPLACE/enabled

---
base-commit: 6d69b6c12fce479fde7bc06f686212451688a102
change-id: 20240525-lp-atomic-replace-90b33ed018dc

Best regards,
-- 
Marcos Paulo de Souza <mpdesouza@suse.com>

Re: [PATCH v2] selftests: livepatch: Test atomic replace against multiple modules

[Petr Mladek]

On Sat 2024-05-25 11:34:08, Marcos Paulo de Souza wrote:
> Adapt the current test-livepatch.sh script to account the number of
> applied livepatches and ensure that an atomic replace livepatch disables
> all previously applied livepatches.
> 
> Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com>

I am not completely sure if it is a good idea to test so many
aspects and use so many different test modules in a single test.
It might be harder to maintain and analyze eventual problems.

But the change will help to catch more problems which is good.
I am fine with it:

Reviewed-by: Petr Mladek <pmladek@suse.com>

Best Regards,
Petr

Re: [PATCH v2] selftests: livepatch: Test atomic replace against multiple modules

[Miroslav Benes]

On Sat, 25 May 2024, Marcos Paulo de Souza wrote:

> diff --git a/tools/testing/selftests/livepatch/test-livepatch.sh b/tools/testing/selftests/livepatch/test-livepatch.sh
> index e3455a6b1158..d85405d18e54 100755
> --- a/tools/testing/selftests/livepatch/test-livepatch.sh
> +++ b/tools/testing/selftests/livepatch/test-livepatch.sh
> @@ -107,9 +107,12 @@ livepatch: '$MOD_LIVEPATCH': unpatching complete
>  
>  # - load a livepatch that modifies the output from /proc/cmdline and
>  #   verify correct behavior
> -# - load an atomic replace livepatch and verify that only the second is active
> -# - remove the first livepatch and verify that the atomic replace livepatch
> -#   is still active
> +# - load two addtional livepatches and check the number of livepatch modules

s/addtional/additional/

Reviewed-by: Miroslav Benes <mbenes@suse.cz>

M

Re: [PATCH v2] selftests: livepatch: Test atomic replace against multiple modules

[Joe Lawrence]

On Sat, May 25, 2024 at 11:34:08AM -0300, Marcos Paulo de Souza wrote:
> Adapt the current test-livepatch.sh script to account the number of
> applied livepatches and ensure that an atomic replace livepatch disables
> all previously applied livepatches.
> 
> Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com>
> ---
> Changes since v1:
> * Added checks in the existing test-livepatch.sh instead of creating a
>   new test file. (Joe)
> * Fixed issues reported by ShellCheck (Joe)
> ---
>  .../testing/selftests/livepatch/test-livepatch.sh  | 46 ++++++++++++++++++++--
>  1 file changed, 42 insertions(+), 4 deletions(-)
> 
> diff --git a/tools/testing/selftests/livepatch/test-livepatch.sh b/tools/testing/selftests/livepatch/test-livepatch.sh
> index e3455a6b1158..d85405d18e54 100755
> --- a/tools/testing/selftests/livepatch/test-livepatch.sh
> +++ b/tools/testing/selftests/livepatch/test-livepatch.sh
> @@ -107,9 +107,12 @@ livepatch: '$MOD_LIVEPATCH': unpatching complete
>  
>  # - load a livepatch that modifies the output from /proc/cmdline and
>  #   verify correct behavior
> -# - load an atomic replace livepatch and verify that only the second is active
> -# - remove the first livepatch and verify that the atomic replace livepatch
> -#   is still active
> +# - load two addtional livepatches and check the number of livepatch modules
> +#   applied
> +# - load an atomic replace livepatch and check that the other three modules were
> +#   disabled
> +# - remove all livepatches besides the atomic replace one and verify that the
> +#   atomic replace livepatch is still active
>  # - remove the atomic replace livepatch and verify that none are active
>  
>  start_test "atomic replace livepatch"
> @@ -119,12 +122,31 @@ load_lp $MOD_LIVEPATCH
>  grep 'live patched' /proc/cmdline > /dev/kmsg
>  grep 'live patched' /proc/meminfo > /dev/kmsg
>  
> +for mod in test_klp_syscall test_klp_callbacks_demo; do

Slightly nitpicky here, but the tests were originally written with the
livepatch module names via variables like $MOD_LIVEPATCH.  Would using
$MOD_LIVEPATCH{1,2,3} help indicate that their specifics aren't really
interesting, that we just need 3 of them?

> +	load_lp $mod
> +done
> +
> +mods=(/sys/kernel/livepatch/*)
> +nmods=${#mods[@]}
> +if [ "$nmods" -ne 3 ]; then
> +	die "Expecting three modules listed, found $nmods"
> +fi
> +

I was going to suggest that we might protect against a situation where
other livepatch modules were active, that a simple count wouldn't be
sufficient.  But then I thought about this test, atomic replace!
Anything previously loaded is going to be pushed aside anyway.

So maybe (in another patch or set) it would be worth enhancing
functions.sh :: start_test() do a quick sanity check to see that the
initial conditions are safe?  That might also prevent some collateral
damage when test A fails and leaves the world a strange place for tests
B, C, etc.

>  load_lp $MOD_REPLACE replace=1
>  
>  grep 'live patched' /proc/cmdline > /dev/kmsg
>  grep 'live patched' /proc/meminfo > /dev/kmsg
>  
> -unload_lp $MOD_LIVEPATCH
> +mods=(/sys/kernel/livepatch/*)
> +nmods=${#mods[@]}
> +if [ "$nmods" -ne 1 ]; then
> +	die "Expecting only one moduled listed, found $nmods"
> +fi
> +
> +# These modules were disabled by the atomic replace
> +for mod in test_klp_callbacks_demo test_klp_syscall $MOD_LIVEPATCH; do
> +	unload_lp "$mod"
> +done
>  
>  grep 'live patched' /proc/cmdline > /dev/kmsg
>  grep 'live patched' /proc/meminfo > /dev/kmsg
> @@ -142,6 +164,20 @@ livepatch: '$MOD_LIVEPATCH': starting patching transition
>  livepatch: '$MOD_LIVEPATCH': completing patching transition
>  livepatch: '$MOD_LIVEPATCH': patching complete
>  $MOD_LIVEPATCH: this has been live patched
> +% insmod test_modules/test_klp_syscall.ko

Similar minor nit here, too.  If we think copy/pasting all the $MOD_FOO
is annoying, I am fine with leaving this as is.  I don't have a strong
opinion other than following some convention.

With that, I'm happy to ack as-is or with variable names.

Acked-by: Joe Lawrence <joe.lawrence@redhat.com>

--
Joe

Re: [PATCH v2] selftests: livepatch: Test atomic replace against multiple modules

[Marcos Paulo de Souza]

On Fri, 2024-05-31 at 15:44 -0400, Joe Lawrence wrote:
> On Sat, May 25, 2024 at 11:34:08AM -0300, Marcos Paulo de Souza
> wrote:
> > Adapt the current test-livepatch.sh script to account the number of
> > applied livepatches and ensure that an atomic replace livepatch
> > disables
> > all previously applied livepatches.
> > 
> > Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com>
> > ---
> > Changes since v1:
> > * Added checks in the existing test-livepatch.sh instead of
> > creating a
> >   new test file. (Joe)
> > * Fixed issues reported by ShellCheck (Joe)
> > ---
> >  .../testing/selftests/livepatch/test-livepatch.sh  | 46
> > ++++++++++++++++++++--
> >  1 file changed, 42 insertions(+), 4 deletions(-)
> > 
> > diff --git a/tools/testing/selftests/livepatch/test-livepatch.sh
> > b/tools/testing/selftests/livepatch/test-livepatch.sh
> > index e3455a6b1158..d85405d18e54 100755
> > --- a/tools/testing/selftests/livepatch/test-livepatch.sh
> > +++ b/tools/testing/selftests/livepatch/test-livepatch.sh
> > @@ -107,9 +107,12 @@ livepatch: '$MOD_LIVEPATCH': unpatching
> > complete
> >  
> >  # - load a livepatch that modifies the output from /proc/cmdline
> > and
> >  #   verify correct behavior
> > -# - load an atomic replace livepatch and verify that only the
> > second is active
> > -# - remove the first livepatch and verify that the atomic replace
> > livepatch
> > -#   is still active
> > +# - load two addtional livepatches and check the number of
> > livepatch modules
> > +#   applied
> > +# - load an atomic replace livepatch and check that the other
> > three modules were
> > +#   disabled
> > +# - remove all livepatches besides the atomic replace one and
> > verify that the
> > +#   atomic replace livepatch is still active
> >  # - remove the atomic replace livepatch and verify that none are
> > active
> >  
> >  start_test "atomic replace livepatch"
> > @@ -119,12 +122,31 @@ load_lp $MOD_LIVEPATCH
> >  grep 'live patched' /proc/cmdline > /dev/kmsg
> >  grep 'live patched' /proc/meminfo > /dev/kmsg
> >  
> > +for mod in test_klp_syscall test_klp_callbacks_demo; do
> 
> Slightly nitpicky here, but the tests were originally written with
> the
> livepatch module names via variables like $MOD_LIVEPATCH.  Would
> using
> $MOD_LIVEPATCH{1,2,3} help indicate that their specifics aren't
> really
> interesting, that we just need 3 of them?

Makes sense. I thought about it when I was changing the code, but I
didn't want to change it too much, so it was the result. But that makes
sense to have the modules better named.

> 
> > +	load_lp $mod
> > +done
> > +
> > +mods=(/sys/kernel/livepatch/*)
> > +nmods=${#mods[@]}
> > +if [ "$nmods" -ne 3 ]; then
> > +	die "Expecting three modules listed, found $nmods"
> > +fi
> > +
> 
> I was going to suggest that we might protect against a situation
> where
> other livepatch modules were active, that a simple count wouldn't be
> sufficient.  But then I thought about this test, atomic replace!
> Anything previously loaded is going to be pushed aside anyway.
> 
> So maybe (in another patch or set) it would be worth enhancing
> functions.sh :: start_test() do a quick sanity check to see that the
> initial conditions are safe?  That might also prevent some collateral
> damage when test A fails and leaves the world a strange place for
> tests
> B, C, etc.

We have been discussing about start/end functions that would check for
leftover modules... maybe should be a good think to implement soon as
we land more tests.

> 
> >  load_lp $MOD_REPLACE replace=1
> >  
> >  grep 'live patched' /proc/cmdline > /dev/kmsg
> >  grep 'live patched' /proc/meminfo > /dev/kmsg
> >  
> > -unload_lp $MOD_LIVEPATCH
> > +mods=(/sys/kernel/livepatch/*)
> > +nmods=${#mods[@]}
> > +if [ "$nmods" -ne 1 ]; then
> > +	die "Expecting only one moduled listed, found $nmods"
> > +fi
> > +
> > +# These modules were disabled by the atomic replace
> > +for mod in test_klp_callbacks_demo test_klp_syscall
> > $MOD_LIVEPATCH; do
> > +	unload_lp "$mod"
> > +done
> >  
> >  grep 'live patched' /proc/cmdline > /dev/kmsg
> >  grep 'live patched' /proc/meminfo > /dev/kmsg
> > @@ -142,6 +164,20 @@ livepatch: '$MOD_LIVEPATCH': starting patching
> > transition
> >  livepatch: '$MOD_LIVEPATCH': completing patching transition
> >  livepatch: '$MOD_LIVEPATCH': patching complete
> >  $MOD_LIVEPATCH: this has been live patched
> > +% insmod test_modules/test_klp_syscall.ko
> 
> Similar minor nit here, too.  If we think copy/pasting all the
> $MOD_FOO
> is annoying, I am fine with leaving this as is.  I don't have a
> strong
> opinion other than following some convention.
> 
> With that, I'm happy to ack as-is or with variable names.

Thanks Joe! I think that is Petr's call, either way I can rework this
patch, or send additional ones to adjust the tests.

> 
> Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
> 
> --
> Joe
> 

Re: [PATCH v2] selftests: livepatch: Test atomic replace against multiple modules

[Petr Mladek]

On Fri 2024-05-31 18:06:48, Marcos Paulo de Souza wrote:
> On Fri, 2024-05-31 at 15:44 -0400, Joe Lawrence wrote:
> > On Sat, May 25, 2024 at 11:34:08AM -0300, Marcos Paulo de Souza
> > wrote:
> > > Adapt the current test-livepatch.sh script to account the number of
> > > applied livepatches and ensure that an atomic replace livepatch
> > > disables
> > > all previously applied livepatches.
> > > 
> > > Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com>
> > > ---
> > > Changes since v1:
> > > * Added checks in the existing test-livepatch.sh instead of
> > > creating a
> > >   new test file. (Joe)
> > > * Fixed issues reported by ShellCheck (Joe)
> > > ---
> > >  .../testing/selftests/livepatch/test-livepatch.sh  | 46
> > > ++++++++++++++++++++--
> > >  1 file changed, 42 insertions(+), 4 deletions(-)
> > > 
> > > diff --git a/tools/testing/selftests/livepatch/test-livepatch.sh
> > > b/tools/testing/selftests/livepatch/test-livepatch.sh
> > > index e3455a6b1158..d85405d18e54 100755
> > > --- a/tools/testing/selftests/livepatch/test-livepatch.sh
> > > +++ b/tools/testing/selftests/livepatch/test-livepatch.sh
> > > @@ -107,9 +107,12 @@ livepatch: '$MOD_LIVEPATCH': unpatching
> > > complete
> > >  
> > >  # - load a livepatch that modifies the output from /proc/cmdline
> > > and
> > >  #   verify correct behavior
> > > -# - load an atomic replace livepatch and verify that only the
> > > second is active
> > > -# - remove the first livepatch and verify that the atomic replace
> > > livepatch
> > > -#   is still active
> > > +# - load two addtional livepatches and check the number of
> > > livepatch modules
> > > +#   applied
> > > +# - load an atomic replace livepatch and check that the other
> > > three modules were
> > > +#   disabled
> > > +# - remove all livepatches besides the atomic replace one and
> > > verify that the
> > > +#   atomic replace livepatch is still active
> > >  # - remove the atomic replace livepatch and verify that none are
> > > active
> > >  
> > >  start_test "atomic replace livepatch"
> > > @@ -119,12 +122,31 @@ load_lp $MOD_LIVEPATCH
> > >  grep 'live patched' /proc/cmdline > /dev/kmsg
> > >  grep 'live patched' /proc/meminfo > /dev/kmsg
> > >  
> > > +for mod in test_klp_syscall test_klp_callbacks_demo; do
> > 
> > Slightly nitpicky here, but the tests were originally written with
> > the
> > livepatch module names via variables like $MOD_LIVEPATCH.  Would
> > using
> > $MOD_LIVEPATCH{1,2,3} help indicate that their specifics aren't
> > really
> > interesting, that we just need 3 of them?
> 
> Makes sense. I thought about it when I was changing the code, but I
> didn't want to change it too much, so it was the result. But that makes
> sense to have the modules better named.

I like this.

> > > +	load_lp $mod
> > > +done
> > > +
> > > +mods=(/sys/kernel/livepatch/*)
> > > +nmods=${#mods[@]}
> > > +if [ "$nmods" -ne 3 ]; then
> > > +	die "Expecting three modules listed, found $nmods"
> > > +fi
> > > +
> > 
> > I was going to suggest that we might protect against a situation
> > where
> > other livepatch modules were active, that a simple count wouldn't be
> > sufficient.  But then I thought about this test, atomic replace!
> > Anything previously loaded is going to be pushed aside anyway.
> > 
> > So maybe (in another patch or set) it would be worth enhancing
> > functions.sh :: start_test() do a quick sanity check to see that the
> > initial conditions are safe?  That might also prevent some collateral
> > damage when test A fails and leaves the world a strange place for
> > tests
> > B, C, etc.
> 
> We have been discussing about start/end functions that would check for
> leftover modules... maybe should be a good think to implement soon as
> we land more tests.

Makes sense :-)

> > >  load_lp $MOD_REPLACE replace=1
> > >  
> > >  grep 'live patched' /proc/cmdline > /dev/kmsg
> > >  grep 'live patched' /proc/meminfo > /dev/kmsg
> > >  
> > > -unload_lp $MOD_LIVEPATCH
> > > +mods=(/sys/kernel/livepatch/*)
> > > +nmods=${#mods[@]}
> > > +if [ "$nmods" -ne 1 ]; then
> > > +	die "Expecting only one moduled listed, found $nmods"
> > > +fi
> > > +
> > > +# These modules were disabled by the atomic replace
> > > +for mod in test_klp_callbacks_demo test_klp_syscall
> > > $MOD_LIVEPATCH; do
> > > +	unload_lp "$mod"
> > > +done
> > >  
> > >  grep 'live patched' /proc/cmdline > /dev/kmsg
> > >  grep 'live patched' /proc/meminfo > /dev/kmsg
> > > @@ -142,6 +164,20 @@ livepatch: '$MOD_LIVEPATCH': starting patching
> > > transition
> > >  livepatch: '$MOD_LIVEPATCH': completing patching transition
> > >  livepatch: '$MOD_LIVEPATCH': patching complete
> > >  $MOD_LIVEPATCH: this has been live patched
> > > +% insmod test_modules/test_klp_syscall.ko
> > 
> > Similar minor nit here, too.  If we think copy/pasting all the
> > $MOD_FOO
> > is annoying, I am fine with leaving this as is.  I don't have a
> > strong
> > opinion other than following some convention.
> > 
> > With that, I'm happy to ack as-is or with variable names.
> 
> Thanks Joe! I think that is Petr's call, either way I can rework this
> patch, or send additional ones to adjust the tests.

I would prefer if you did respin this patch. The use of
$MOD_LIVEPATCH{1,2,3} would make even the patch easier to follow.

Best Regards,
Petr

Re: [PATCH v2] selftests: livepatch: Test atomic replace against multiple modules

[Marcos Paulo de Souza]

On Mon, 2024-06-03 at 14:52 +0200, Petr Mladek wrote:
> On Fri 2024-05-31 18:06:48, Marcos Paulo de Souza wrote:
> > On Fri, 2024-05-31 at 15:44 -0400, Joe Lawrence wrote:
> > > On Sat, May 25, 2024 at 11:34:08AM -0300, Marcos Paulo de Souza
> > > wrote:
> > > > Adapt the current test-livepatch.sh script to account the
> > > > number of
> > > > applied livepatches and ensure that an atomic replace livepatch
> > > > disables
> > > > all previously applied livepatches.
> > > > 
> > > > Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com>
> > > > ---
> > > > Changes since v1:
> > > > * Added checks in the existing test-livepatch.sh instead of
> > > > creating a
> > > >   new test file. (Joe)
> > > > * Fixed issues reported by ShellCheck (Joe)
> > > > ---
> > > >  .../testing/selftests/livepatch/test-livepatch.sh  | 46
> > > > ++++++++++++++++++++--
> > > >  1 file changed, 42 insertions(+), 4 deletions(-)
> > > > 
> > > > diff --git a/tools/testing/selftests/livepatch/test-
> > > > livepatch.sh
> > > > b/tools/testing/selftests/livepatch/test-livepatch.sh
> > > > index e3455a6b1158..d85405d18e54 100755
> > > > --- a/tools/testing/selftests/livepatch/test-livepatch.sh
> > > > +++ b/tools/testing/selftests/livepatch/test-livepatch.sh
> > > > @@ -107,9 +107,12 @@ livepatch: '$MOD_LIVEPATCH': unpatching
> > > > complete
> > > >  
> > > >  # - load a livepatch that modifies the output from
> > > > /proc/cmdline
> > > > and
> > > >  #   verify correct behavior
> > > > -# - load an atomic replace livepatch and verify that only the
> > > > second is active
> > > > -# - remove the first livepatch and verify that the atomic
> > > > replace
> > > > livepatch
> > > > -#   is still active
> > > > +# - load two addtional livepatches and check the number of
> > > > livepatch modules
> > > > +#   applied
> > > > +# - load an atomic replace livepatch and check that the other
> > > > three modules were
> > > > +#   disabled
> > > > +# - remove all livepatches besides the atomic replace one and
> > > > verify that the
> > > > +#   atomic replace livepatch is still active
> > > >  # - remove the atomic replace livepatch and verify that none
> > > > are
> > > > active
> > > >  
> > > >  start_test "atomic replace livepatch"
> > > > @@ -119,12 +122,31 @@ load_lp $MOD_LIVEPATCH
> > > >  grep 'live patched' /proc/cmdline > /dev/kmsg
> > > >  grep 'live patched' /proc/meminfo > /dev/kmsg
> > > >  
> > > > +for mod in test_klp_syscall test_klp_callbacks_demo; do
> > > 
> > > Slightly nitpicky here, but the tests were originally written
> > > with
> > > the
> > > livepatch module names via variables like $MOD_LIVEPATCH.  Would
> > > using
> > > $MOD_LIVEPATCH{1,2,3} help indicate that their specifics aren't
> > > really
> > > interesting, that we just need 3 of them?
> > 
> > Makes sense. I thought about it when I was changing the code, but I
> > didn't want to change it too much, so it was the result. But that
> > makes
> > sense to have the modules better named.
> 
> I like this.
> 
> > > > +	load_lp $mod
> > > > +done
> > > > +
> > > > +mods=(/sys/kernel/livepatch/*)
> > > > +nmods=${#mods[@]}
> > > > +if [ "$nmods" -ne 3 ]; then
> > > > +	die "Expecting three modules listed, found $nmods"
> > > > +fi
> > > > +
> > > 
> > > I was going to suggest that we might protect against a situation
> > > where
> > > other livepatch modules were active, that a simple count wouldn't
> > > be
> > > sufficient.  But then I thought about this test, atomic replace!
> > > Anything previously loaded is going to be pushed aside anyway.
> > > 
> > > So maybe (in another patch or set) it would be worth enhancing
> > > functions.sh :: start_test() do a quick sanity check to see that
> > > the
> > > initial conditions are safe?  That might also prevent some
> > > collateral
> > > damage when test A fails and leaves the world a strange place for
> > > tests
> > > B, C, etc.
> > 
> > We have been discussing about start/end functions that would check
> > for
> > leftover modules... maybe should be a good think to implement soon
> > as
> > we land more tests.
> 
> Makes sense :-)
> 
> > > >  load_lp $MOD_REPLACE replace=1
> > > >  
> > > >  grep 'live patched' /proc/cmdline > /dev/kmsg
> > > >  grep 'live patched' /proc/meminfo > /dev/kmsg
> > > >  
> > > > -unload_lp $MOD_LIVEPATCH
> > > > +mods=(/sys/kernel/livepatch/*)
> > > > +nmods=${#mods[@]}
> > > > +if [ "$nmods" -ne 1 ]; then
> > > > +	die "Expecting only one moduled listed, found $nmods"
> > > > +fi
> > > > +
> > > > +# These modules were disabled by the atomic replace
> > > > +for mod in test_klp_callbacks_demo test_klp_syscall
> > > > $MOD_LIVEPATCH; do
> > > > +	unload_lp "$mod"
> > > > +done
> > > >  
> > > >  grep 'live patched' /proc/cmdline > /dev/kmsg
> > > >  grep 'live patched' /proc/meminfo > /dev/kmsg
> > > > @@ -142,6 +164,20 @@ livepatch: '$MOD_LIVEPATCH': starting
> > > > patching
> > > > transition
> > > >  livepatch: '$MOD_LIVEPATCH': completing patching transition
> > > >  livepatch: '$MOD_LIVEPATCH': patching complete
> > > >  $MOD_LIVEPATCH: this has been live patched
> > > > +% insmod test_modules/test_klp_syscall.ko
> > > 
> > > Similar minor nit here, too.  If we think copy/pasting all the
> > > $MOD_FOO
> > > is annoying, I am fine with leaving this as is.  I don't have a
> > > strong
> > > opinion other than following some convention.
> > > 
> > > With that, I'm happy to ack as-is or with variable names.
> > 
> > Thanks Joe! I think that is Petr's call, either way I can rework
> > this
> > patch, or send additional ones to adjust the tests.
> 
> I would prefer if you did respin this patch. The use of
> $MOD_LIVEPATCH{1,2,3} would make even the patch easier to follow.

Done in v3. About the pre-check, I discussed with Miroslav about having
an easier way to skip tests. The idea was to split each "test" into a
different file, like fstests already does. Using this approach, each
start_test function will be placed in a different file to test
specifically one functionality. This way we can skip a test if we don't
have some requirements (like a sysfs attribute for example, or the
there were leftover modules).

I plan to send a patch starting this move when the v3 of this patchset
is accepted.

> 
> Best Regards,
> Petr