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References: <20231204221932.1465004-1-rmoar@google.com> <20231204221932.1465004-5-rmoar@google.com>
In-Reply-To: <20231204221932.1465004-5-rmoar@google.com>
From:   David Gow <davidgow@google.com>
Date:   Sat, 9 Dec 2023 15:57:53 +0800
Message-ID: <CABVgOSngSGgxmc-6gENvZfgVK4DTpHXoPZagAcikyd1CMnaoBg@mail.gmail.com>
Subject: Re: [PATCH v3 5/6] kunit: add ability to run tests after boot using debugfs
To:     Rae Moar <rmoar@google.com>
Cc:     shuah@kernel.org, dlatypov@google.com, brendan.higgins@linux.dev,
        sadiyakazi@google.com, keescook@chromium.org, arnd@arndb.de,
        linux-kselftest@vger.kernel.org, linux-arch@vger.kernel.org,
        kunit-dev@googlegroups.com, linux-kernel@vger.kernel.org
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On Tue, 5 Dec 2023 at 06:19, Rae Moar <rmoar@google.com> wrote:
>
> Add functionality to run built-in tests after boot by writing to a
> debugfs file.
>
> Add a new debugfs file labeled "run" for each test suite to use for
> this purpose.
>
> As an example, write to the file using the following:
>
> echo "any string" > /sys/kernel/debugfs/kunit/<testsuite>/run
>
> This will trigger the test suite to run and will print results to the
> kernel log.
>
> To guard against running tests concurrently with this feature, add a
> mutex lock around running kunit. This supports the current practice of
> not allowing tests to be run concurrently on the same kernel.
>
> This new functionality could be used to design a parameter
> injection feature in the future.
>
> Signed-off-by: Rae Moar <rmoar@google.com>
> ---

This looks good to me.

A future feature which may be useful would be to support other kunit
actions here (like list, list_attr), but that's probably worth leaving
as a follow-up.

Reviewed-by: David Gow <davidgow@google.com>

Cheers,
-- David


>
> Changes since v2:
> - Move resetting the log to test.c
> - Add is_init attribute and patches to change linker sections to avoid
>   re-running tests that use init data and functions
>
>  lib/kunit/debugfs.c | 68 +++++++++++++++++++++++++++++++++++++++++++++
>  lib/kunit/test.c    | 10 +++++++
>  2 files changed, 78 insertions(+)
>
> diff --git a/lib/kunit/debugfs.c b/lib/kunit/debugfs.c
> index 270d185737e6..2e0a92a0c461 100644
> --- a/lib/kunit/debugfs.c
> +++ b/lib/kunit/debugfs.c
> @@ -8,12 +8,14 @@
>  #include <linux/module.h>
>
>  #include <kunit/test.h>
> +#include <kunit/test-bug.h>
>
>  #include "string-stream.h"
>  #include "debugfs.h"
>
>  #define KUNIT_DEBUGFS_ROOT             "kunit"
>  #define KUNIT_DEBUGFS_RESULTS          "results"
> +#define KUNIT_DEBUGFS_RUN              "run"
>
>  /*
>   * Create a debugfs representation of test suites:
> @@ -21,6 +23,8 @@
>   * Path                                                Semantics
>   * /sys/kernel/debug/kunit/<testsuite>/results Show results of last run for
>   *                                             testsuite
> + * /sys/kernel/debug/kunit/<testsuite>/run     Write to this file to trigger
> + *                                             testsuite to run
>   *
>   */
>
> @@ -99,6 +103,51 @@ static int debugfs_results_open(struct inode *inode, struct file *file)
>         return single_open(file, debugfs_print_results, suite);
>  }
>
> +/*
> + * Print a usage message to the debugfs "run" file
> + * (/sys/kernel/debug/kunit/<testsuite>/run) if opened.
> + */
> +static int debugfs_print_run(struct seq_file *seq, void *v)
> +{
> +       struct kunit_suite *suite = (struct kunit_suite *)seq->private;
> +
> +       seq_puts(seq, "Write to this file to trigger the test suite to run.\n");
> +       seq_printf(seq, "usage: echo \"any string\" > /sys/kernel/debugfs/kunit/%s/run\n",
> +                       suite->name);
> +       return 0;
> +}
> +
> +/*
> + * The debugfs "run" file (/sys/kernel/debug/kunit/<testsuite>/run)
> + * contains no information. Write to the file to trigger the test suite
> + * to run.
> + */
> +static int debugfs_run_open(struct inode *inode, struct file *file)
> +{
> +       struct kunit_suite *suite;
> +
> +       suite = (struct kunit_suite *)inode->i_private;
> +
> +       return single_open(file, debugfs_print_run, suite);
> +}
> +
> +/*
> + * Trigger a test suite to run by writing to the suite's "run" debugfs
> + * file found at: /sys/kernel/debug/kunit/<testsuite>/run
> + *
> + * Note: what is written to this file will not be saved.
> + */
> +static ssize_t debugfs_run(struct file *file,
> +               const char __user *buf, size_t count, loff_t *ppos)
> +{
> +       struct inode *f_inode = file->f_inode;
> +       struct kunit_suite *suite = (struct kunit_suite *) f_inode->i_private;
> +
> +       __kunit_test_suites_init(&suite, 1);
> +
> +       return count;
> +}
> +
>  static const struct file_operations debugfs_results_fops = {
>         .open = debugfs_results_open,
>         .read = seq_read,
> @@ -106,10 +155,22 @@ static const struct file_operations debugfs_results_fops = {
>         .release = debugfs_release,
>  };
>
> +static const struct file_operations debugfs_run_fops = {
> +       .open = debugfs_run_open,
> +       .read = seq_read,
> +       .write = debugfs_run,
> +       .llseek = seq_lseek,
> +       .release = debugfs_release,
> +};
> +
>  void kunit_debugfs_create_suite(struct kunit_suite *suite)
>  {
>         struct kunit_case *test_case;
>
> +       /* If suite log already allocated, do not create new debugfs files. */
> +       if (suite->log)
> +               return;
> +
>         /* Allocate logs before creating debugfs representation. */
>         suite->log = alloc_string_stream(GFP_KERNEL);
>         string_stream_set_append_newlines(suite->log, true);
> @@ -124,6 +185,13 @@ void kunit_debugfs_create_suite(struct kunit_suite *suite)
>         debugfs_create_file(KUNIT_DEBUGFS_RESULTS, S_IFREG | 0444,
>                             suite->debugfs,
>                             suite, &debugfs_results_fops);
> +
> +       /* Do not create file to re-run test if test runs on init */
> +       if (!suite->attr.is_init) {
> +               debugfs_create_file(KUNIT_DEBUGFS_RUN, S_IFREG | 0644,
> +                                   suite->debugfs,
> +                                   suite, &debugfs_run_fops);
> +       }
>  }
>
>  void kunit_debugfs_destroy_suite(struct kunit_suite *suite)
> diff --git a/lib/kunit/test.c b/lib/kunit/test.c
> index 8bae6e2bc6a0..58e46bb3b4c4 100644
> --- a/lib/kunit/test.c
> +++ b/lib/kunit/test.c
> @@ -13,6 +13,7 @@
>  #include <linux/kernel.h>
>  #include <linux/module.h>
>  #include <linux/moduleparam.h>
> +#include <linux/mutex.h>
>  #include <linux/panic.h>
>  #include <linux/sched/debug.h>
>  #include <linux/sched.h>
> @@ -22,6 +23,8 @@
>  #include "string-stream.h"
>  #include "try-catch-impl.h"
>
> +static DEFINE_MUTEX(kunit_run_lock);
> +
>  /*
>   * Hook to fail the current test and print an error message to the log.
>   */
> @@ -654,6 +657,7 @@ static void kunit_init_suite(struct kunit_suite *suite)
>         kunit_debugfs_create_suite(suite);
>         suite->status_comment[0] = '\0';
>         suite->suite_init_err = 0;
> +       string_stream_clear(suite->log);
>  }
>
>  bool kunit_enabled(void)
> @@ -670,6 +674,11 @@ int __kunit_test_suites_init(struct kunit_suite * const * const suites, int num_
>                 return 0;
>         }
>
> +       /* Use mutex lock to guard against running tests concurrently. */
> +       if (mutex_lock_interruptible(&kunit_run_lock)) {
> +               pr_err("kunit: test interrupted\n");
> +               return -EINTR;
> +       }
>         static_branch_inc(&kunit_running);
>
>         for (i = 0; i < num_suites; i++) {
> @@ -678,6 +687,7 @@ int __kunit_test_suites_init(struct kunit_suite * const * const suites, int num_
>         }
>
>         static_branch_dec(&kunit_running);
> +       mutex_unlock(&kunit_run_lock);
>         return 0;
>  }
>  EXPORT_SYMBOL_GPL(__kunit_test_suites_init);
> --
> 2.43.0.rc2.451.g8631bc7472-goog
>

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