michaelh/zephyr
1
0
Fork 0
Code Releases Activity

kernel/poll: Move "_poller" into thread struct, fix COHERENCE collision

Browse source 
Fix the issue where the kernel poll code would place the tracking
struct on the caller stack and share it with other threads, thus
creating a cache coherence issue on systems where KERNEL_COHERENCE is
enabled.

This works by eliminating the thread backpointer in struct _poller and
simply placing the (now just two-byte!) struct directly into the
thread struct.

Note that this doesn't attempt to fix the API paradigm that the
natural way to structure a call to k_poll() is to use an array of
k_poll_events on the CALLER's stack.  So it's likely that most
"typical" k_poll code is still going to have problems with
KERNEL_COHERENCE.  But at least now the kernel internals aren't
fundamentally broken.

Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
This commit is contained in:
Andy Ross 2020-11-09 15:17:18 -08:00 • committed by Anas Nashif
commit dadc6643e4
2 changed files with 28 additions and 33 deletions
Download patch file Download diff file Expand all files Collapse all files

21
include/kernel.h
View file

@ -272,6 +272,14 @@ struct _thread_userspace_local_data {
};
#endif
/* private, used by k_poll and k_work_poll */
struct k_work_poll;
typedef int (*_poller_cb_t)(struct k_poll_event *event, uint32_t state);
struct _poller {
bool is_polling;
uint8_t mode;
};
/**
* @ingroup thread_apis
* Thread Structure
@ -309,6 +317,10 @@ struct k_thread {
*/
void (*fn_abort)(struct k_thread *aborted);
#if defined(CONFIG_POLL)
struct _poller poller;
#endif
#if defined(CONFIG_THREAD_MONITOR)
/** thread entry and parameters description */
struct __thread_entry entry;
@ -2710,15 +2722,6 @@ __syscall int k_stack_pop(struct k_stack *stack, stack_data_t *data,
/** @} */
struct k_work;
struct k_work_poll;
/* private, used by k_poll and k_work_poll */
typedef int (*_poller_cb_t)(struct k_poll_event *event, uint32_t state);
struct _poller {
volatile bool is_polling;
struct k_thread *thread;
uint8_t mode;
};
/**
* @addtogroup thread_apis