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kernel/queue: Remove interior use of k_poll()

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The k_queue data structure, when CONFIG_POLL was enabled, would
inexplicably use k_poll() as its blocking mechanism instead of the
original wait_q/pend() code.  This was actually racy, see commit
b173e4353f.  The code was structured as a condition variable: using
a spinlock around the queue data before deciding to block.  But unlike
pend_current_thread(), k_poll() cannot atomically release a lock.

A workaround had been in place for this, and then accidentally
reverted (both by me!) because the code looked "wrong".

This is just fragile, there's no reason to have two implementations of
k_queue_get().  Remove.

Note that this also removes a test case in the work_queue test where
(when CONFIG_POLL was enabled, but not otherwise) it was checking for
the ability to immediately cancel a delayed work item that was
submitted with a timeout of K_NO_WAIT (i.e. "queue it immediately").
This DOES NOT work with the origina/non-poll queue backend, and has
never been a documented behavior of k_delayed_work_submit_to_queue()
under any circumstances.  I don't know why we were testing this.

Fixes #25904

Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
This commit is contained in:
Andy Ross 2020-06-02 08:34:12 -07:00 • committed by Carles Cufí
commit 99c2d2d047
3 changed files with 8 additions and 70 deletions
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13
include/kernel.h
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@ -2155,12 +2155,9 @@ static inline u32_t k_cycle_get_32(void)
struct k_queue {
sys_sflist_t data_q;
struct k_spinlock lock;
union {
_wait_q_t wait_q;
_POLL_EVENT;
};
_wait_q_t wait_q;
_POLL_EVENT;
_OBJECT_TRACING_NEXT_PTR(k_queue)
_OBJECT_TRACING_LINKED_FLAG
};
@ -2169,10 +2166,8 @@ struct k_queue {
{ \
.data_q = SYS_SLIST_STATIC_INIT(&obj.data_q), \
.lock = { }, \
{ \
.wait_q = Z_WAIT_Q_INIT(&obj.wait_q), \
_POLL_EVENT_OBJ_INIT(obj) \
}, \
.wait_q = Z_WAIT_Q_INIT(&obj.wait_q), \
_POLL_EVENT_OBJ_INIT(obj) \
_OBJECT_TRACING_INIT \
}