Reset the inherited cpu affinity

[ningmingxiao]

since this patch https://lore.kernel.org/lkml/20231003205735.2921964-1-longman@redhat.com/ doesn't merge into kernel.
so it doesn't work on new kernel. @giuseppe

[sourcery-ai]

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

This PR updates libcrun_reset_cpu_affinity_mask to explicitly build and apply a full CPU affinity mask instead of relying on the kernel’s default behavior.

Class diagram for updated libcrun_reset_cpu_affinity_mask function

classDiagram
    class libcrun_reset_cpu_affinity_mask {
        +int libcrun_reset_cpu_affinity_mask(pid_t pid, libcrun_error_t *err)
        -int ret
        -cpu_set_t mask
        -long cpu_num
    }

Loading

File-Level Changes

Change	Details	Files
Explicitly set the CPU affinity mask to all available CPUs	Declare a cpu_set_t variable for the mask Use sysconf(_SC_NPROCESSORS_CONF) to get the number of CPUs Loop over CPU indices and add each to the mask Call sched_setaffinity with sizeof(mask) and &mask instead of NULL	src/libcrun/scheduler.c

---

Tips and commands

Interacting with Sourcery

• Trigger a new review: Comment @sourcery-ai review on the pull request.
• Continue discussions: Reply directly to Sourcery's review comments.
• Generate a GitHub issue from a review comment: Ask Sourcery to create an
  issue from a review comment by replying to it. You can also reply to a
  review comment with @sourcery-ai issue to create an issue from it.
• Generate a pull request title: Write @sourcery-ai anywhere in the pull
  request title to generate a title at any time. You can also comment
  @sourcery-ai title on the pull request to (re-)generate the title at any time.
• Generate a pull request summary: Write @sourcery-ai summary anywhere in
  the pull request body to generate a PR summary at any time exactly where you
  want it. You can also comment @sourcery-ai summary on the pull request to
  (re-)generate the summary at any time.
• Generate reviewer's guide: Comment @sourcery-ai guide on the pull
  request to (re-)generate the reviewer's guide at any time.
• Resolve all Sourcery comments: Comment @sourcery-ai resolve on the
  pull request to resolve all Sourcery comments. Useful if you've already
  addressed all the comments and don't want to see them anymore.
• Dismiss all Sourcery reviews: Comment @sourcery-ai dismiss on the pull
  request to dismiss all existing Sourcery reviews. Especially useful if you
  want to start fresh with a new review - don't forget to comment
  @sourcery-ai review to trigger a new review!

Customizing Your Experience

Access your dashboard to:

• Enable or disable review features such as the Sourcery-generated pull request
  summary, the reviewer's guide, and others.
• Change the review language.
• Add, remove or edit custom review instructions.
• Adjust other review settings.

Getting Help

• Contact our support team for questions or feedback.
• Visit our documentation for detailed guides and information.
• Keep in touch with the Sourcery team by following us on X/Twitter, LinkedIn or GitHub.

[sourcery-ai]

Hey there - I've reviewed your changes and they look great!

Prompt for AI Agents

Please address the comments from this code review:

## Individual Comments

### Comment 1
<location> `src/libcrun/scheduler.c:85-88` </location>
<code_context>
 libcrun_reset_cpu_affinity_mask (pid_t pid, libcrun_error_t *err)
 {
   int ret;
+  cpu_set_t mask;
+
+  long cpu_num = sysconf(_SC_NPROCESSORS_CONF);
+  for (int i = 0; i < cpu_num; i++) {
+        CPU_SET(i, &mask);
+  }
</code_context>

<issue_to_address>
**issue (bug_risk):** mask is not initialized before use, which may lead to undefined behavior.

Initialize mask with CPU_ZERO(&mask) before using CPU_SET to avoid unintended affinity settings.
</issue_to_address>

### Comment 2
<location> `src/libcrun/scheduler.c:87` </location>
<code_context>
   int ret;
+  cpu_set_t mask;
+
+  long cpu_num = sysconf(_SC_NPROCESSORS_CONF);
+  for (int i = 0; i < cpu_num; i++) {
+        CPU_SET(i, &mask);
</code_context>

<issue_to_address>
**issue:** sysconf(_SC_NPROCESSORS_CONF) can return -1 on error, which is not handled.

Check if cpu_num is -1 before using it in the loop to prevent undefined behavior.
</issue_to_address>

### Comment 3
<location> `src/libcrun/scheduler.c:104` </location>
<code_context>
      See: https://issues.redhat.com/browse/OCPBUGS-15102   */
-  ret = sched_setaffinity (pid, 0, NULL);
+  ret = sched_setaffinity (pid, sizeof(mask), &mask);
   if (LIKELY (ret < 0))
     {
       if (LIKELY (errno == EINVAL || errno == ENODEV || errno == ENOSYS))
</code_context>

<issue_to_address>
**nitpick:** The logic for error checking on sched_setaffinity return value appears inverted.

The use of LIKELY with ret < 0 may reduce clarity, as errors are less likely. Please clarify or remove the macro to improve readability.
</issue_to_address>

---

Sourcery is free for open source - if you like our reviews please consider sharing them ✨

• X
• Mastodon
• LinkedIn
• Facebook

_{Help me be more useful! Please click 👍 or 👎 on each comment and I'll use the feedback to improve your reviews.}

[giuseppe]

@haircommander PTAL

[ningmingxiao]

can this pr be merged @giuseppe

[kolyshkin]

LGTM, thanks

[kolyshkin]

just a nit about uneeded CPU_ZERO

[ningmingxiao]

just a nit about uneeded CPU_ZERO

done thanks.

[kolyshkin]

LGTM

@haircommander PTAL

[giuseppe]

LGTM