3998e2a072
Replace the BSD license header with the SPDX tag for files with only an Intel copyright on them. Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
86 lines
2.4 KiB
C
86 lines
2.4 KiB
C
/* SPDX-License-Identifier: BSD-3-Clause
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* Copyright(c) 2015 Intel Corporation
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*/
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#ifndef _PTHREAD_SHIM_H_
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#define _PTHREAD_SHIM_H_
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#include <rte_lcore.h>
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/*
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* This pthread shim is an example that demonstrates how legacy code
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* that makes use of POSIX pthread services can make use of lthreads
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* with reduced porting effort.
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*
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* N.B. The example is not a complete implementation, only a subset of
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* pthread APIs sufficient to demonstrate the principle of operation
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* are implemented.
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*
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* In general pthread attribute objects do not have equivalent functions
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* in lthreads, and are ignored.
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*
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* There is one exception and that is the use of attr to specify a
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* core affinity in calls to pthread_create.
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*
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* The shim operates as follows:-
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*
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* On initialisation a constructor function uses dlsym to obtain and
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* save the loaded address of the full set of pthread APIs that will
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* be overridden.
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*
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* For each function there is a stub provided that will invoke either
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* the genuine pthread library function saved saved by the constructor,
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* or else the corresponding equivalent lthread function.
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*
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* The stub functions are implemented in pthread_shim.c
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*
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* The stub will take care of adapting parameters, and any police
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* any constraints where lthread functionality differs.
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*
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* The initial thread must always be a pure lthread.
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*
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* The decision whether to invoke the real library function or the lthread
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* function is controlled by a per pthread flag that can be switched
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* on of off by the pthread_override_set() API described below. Typcially
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* this should be done as the first action of the initial lthread.
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*
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* N.B In general it would be poor practice to revert to invoke a real
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* pthread function when running as an lthread, since these may block and
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* effectively stall the lthread scheduler.
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*
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*/
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/*
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* An exiting lthread must not terminate the pthread it is running in
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* since this would mean terminating the lthread scheduler.
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* We override pthread_exit() with a macro because it is typically declared with
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* __attribute__((noreturn))
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*/
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void pthread_exit_override(void *v);
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#define pthread_exit(v) do { \
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pthread_exit_override((v)); \
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return NULL; \
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} while (0)
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/*
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* Enable/Disable pthread override
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* state
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* 0 disable
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* 1 enable
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*/
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void pthread_override_set(int state);
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/*
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* Return pthread override state
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* return
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* 0 disable
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* 1 enable
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*/
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int pthread_override_get(void);
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#endif /* _PTHREAD_SHIM_H_ */
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