kunit_add_action(9)

💅 kunit_add_action(9) 💅

okay bestie, so you know how your kernel test can just abort mid-way and leave a whole mess of allocated memory behind? yeah. this is the function that fixes that. it lives in the Kernel API Manual and it's literally about to be your new fave. ✨

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✨ NAME ✨

kunit_add_action — Call a function when the test ends.

periodt. that's the whole vibe. 🎀

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🌸 SYNOPSIS 🌸

int kunit_add_action (struct kunit *test , kunit_action_t *action , void
*ctx );

like, three args, one job: schedule a lil cleanup callback for when the test is done. no cap. 🫶

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🦋 ARGUMENTS 🦋

• test — the test case you're associating the action with. this is the main character everything hangs off of. 👑
• action — the function that runs on test exit. yes, that one. the cleanup queen. 💅
• ctx — data passed into func. it's the lil care package your callback gets handed. 🍓

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🌈 DESCRIPTION 🌈

okay so here's the tea ☕ — kunit_add_action defers the execution of a function until the test exits, whether that's a normal, happy exit or a full-on failure exit. ctx gets passed in as additional context, so your callback has everything it needs.

and the iconic part? all functions registered with kunit_add_action will execute in the opposite order to that they were registered in. stack behaviour, bestie. last in, first out. the way that actually makes sense for cleanup 😭🔥

this is super useful for cleaning up allocated memory and resources, because these functions get called even if the test aborts early due to, like, a failed assertion. your cleanup does not ghost you. it shows up. 🫶

also see: devm_add_action for the devres equivalent — same energy, different subsystem. iykyk 💜

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💖 RETURN 💖

0 on success. an error if the action could not be deferred. that's it. that's the whole return section. 💀

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🧚 SEE ALSO 🧚

bestie the friend group is LARGE, buckle up:

• Kernel file ./include/kunit/resource.h
• struct kunit_resource(9)
• kunit_get_resource(9)
• kunit_put_resource(9)
• __kunit_add_resource(9)
• kunit_add_resource(9)
• kunit_add_named_resource(9)
• kunit_alloc_and_get_resource(9)
• kunit_alloc_resource(9)
• kunit_resource_name_match(9)
• kunit_find_resource(9)
• kunit_find_named_resource(9)
• kunit_destroy_resource(9)
• kunit_remove_resource(9)
• KUNIT_DEFINE_ACTION_WRAPPER(9)
• kunit_add_action_or_reset(9)
• kunit_remove_action(9)
• kunit_release_action(9)

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💀 reminder bestie: registration order is reversed on execution. don't be the person who forgets that and then wonders why their teardown is backwards. 🙈

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okay that's the whole page!! mwah 💋 this came from ./include/kunit and was dated October 2026, and the page is literally just called kunit_add_action(9). slay, go forth and clean up your resources properly. 🌟💜