kunit_platfo...it_for_probe(9)

💅 kunit_platform_device_prepare_wait_for_probe(9)

okay bestie, welcome to the Kernel API Manual ✨ — this one's a lil helper from the KUnit platform device crowd, and it's genuinely so useful once you get the vibe. Let me spill 🫖

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🌸 NAME 🌸

kunit_platform_device_prepare_wait_for_probe — prepare a completion variable so you can wait for a platform device to probe 🎀

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✨ SYNOPSIS ✨

int kunit_platform_device_prepare_wait_for_probe (struct kunit *test ,
struct platform_device *pdev , struct completion *x );

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🦋 ARGUMENTS 🦋

• test — the test context, your main character ✨
• pdev — the platform device you're getting ready to wait on for its probe 👀
• x — the completion variable that gets completed once the dev has probed 💖

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💜 DESCRIPTION 💜

So basically, this function preps a completion variable x so you can wait for pdev to probe. And here's the lowkey important part: waiting on that completion forces a preemption, which is what lets the platform driver actually go ahead and probe. It's giving "make room so the driver can do its thing" 🧚 no cap.

🍓 Example 🍓

static int kunit_platform_driver_probe(struct platform_device *pdev)
{
        return 0;
}

static void kunit_platform_driver_test(struct kunit *test)
{
        struct platform_device *pdev;
        struct platform_driver *pdrv;
        DECLARE_COMPLETION_ONSTACK(comp);

        pdev = kunit_platform_device_alloc(test, "kunit-platform", -1);
        KUNIT_ASSERT_NOT_ERR_OR_NULL(test, pdev);
        KUNIT_ASSERT_EQ(test, 0, kunit_platform_device_add(test, pdev));

        pdrv = kunit_kzalloc(test, sizeof(*pdrv), GFP_KERNEL);
        KUNIT_ASSERT_NOT_ERR_OR_NULL(test, pdrv);

        pdrv->probe = kunit_platform_driver_probe;
        pdrv->driver.name = "kunit-platform";
        pdrv->driver.owner = THIS_MODULE;

        KUNIT_ASSERT_EQ(test, 0, kunit_platform_device_prepare_wait_for_probe(test, pdev, comp));
        KUNIT_ASSERT_EQ(test, 0, kunit_platform_driver_register(test, pdrv));

        KUNIT_EXPECT_NE(test, 0, wait_for_completion_timeout(comp, 3 * HZ));
}

like, look at that flow 😭 it's iconic. allocate, add, register, wait — periodt.

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🔥 RETURN 🔥

• 0 on success 🎉
• negative errno on failure 💀

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🌈 SEE ALSO 🌈

kernel file ./lib/kunit/platform.c plus its besties:

• kunit_platform_device_alloc(9)
• kunit_platform_device_add(9)
• kunit_platform_device_register_full(9)
• kunit_platform_device_unregister(9)
• kunit_platform_driver_register(9)

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💡 reminder bestie: waiting on the completion is the whole point — it's what forces the preemption so the driver can probe. don't skip the vibe check on that one 🫶

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and that's the whole page! brought to you by <pink>./lib/kunit</pink> 💖 dated <purple>October 2026</purple> 🗓️ — go forth and probe, queen 👑💅