KUNIT_STATIC_STUB_REDIRECT(9)

💅 KUNIT_STATIC_STUB_REDIRECT(9) — like, the whole vibe

okay bestie so this is a page from the Kernel API Manual (yes the Kernel API Manual, we're in the big leagues now) and it's all about KUNIT_STATIC_STUB_REDIRECT — a macro that lets a KUnit test swap out a function on the fly. iconic behaviour, honestly. 🎀

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✨ NAME ✨

KUNIT_STATIC_STUB_REDIRECT — call a replacement "static stub" if one exists 🫶

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🌸 SYNOPSIS 🌸

KUNIT_STATIC_STUB_REDIRECT (real_fn_name , args... );

that's the whole shape of it, periodt ✨

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🦋 ARGUMENTS 🦋

• real_fn_name — the name of this function, and no cap it has to be as an identifier, not a string 🙈 like, don't go putting quotes on it.
• args — literally all of the arguments you passed to this function. every single one. bring the whole squad. 💜

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🔥 DESCRIPTION 🔥

so this thing is a function prologue. it's giving "bouncer at the door of your function" energy 👑 — it's there so that a KUnit test can redirect calls to the current function somewhere else.

here's the tea: KUnit tests can call kunit_activate_static_stub to pass a replacement function in, and that replacement function gets called by KUNIT_STATIC_STUB_REDIRECT, which then returns from the function — like, dips out immediately, bye 💅.

but if the caller is not in a KUnit context? then the function just keeps executing as normal, no drama, business as usual. slay. ✨

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🎀 EXAMPLE 🎀

okay watch, this is the cute part:

int real_func(int n)
{
        KUNIT_STATIC_STUB_REDIRECT(real_func, n);
        return 0;
}

int replacement_func(int n)
{
        return 42;
}

void example_test(struct kunit *test)
{
        kunit_activate_static_stub(test, real_func, replacement_func);
        KUNIT_EXPECT_EQ(test, real_func(1), 42);
}

see how real_func(1) comes back as 42? that's the stub doing its little magic trick 🧚 nobody touch anything, it's working.

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🌈 SEE ALSO 🌈

• the kernel file ./include/kunit/static_stub.h — go read it, iykyk 📖
• kunit_activate_static_stub(9)
• kunit_deactivate_static_stub(9)

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and that's the page, bestie!! no notes, 10/10, ate and left no crumbs 🍓

source/version: ./include/kunit · date: October 2026 · KUNIT_STATIC_STUB_REDIRECT(9) — mwah, see u in the next manpage 💖🦋🌸