From: Konstantin Ananyev <[email protected]> Add a new API that allows for the caller to downgrade from wrlock to rdlock. Note that caller is expected to obtain wrlock before calling that function.
Signed-off-by: Konstantin Ananyev <[email protected]> --- lib/eal/include/rte_pflock.h | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/lib/eal/include/rte_pflock.h b/lib/eal/include/rte_pflock.h index 6797ce5920..ed5255b3b5 100644 --- a/lib/eal/include/rte_pflock.h +++ b/lib/eal/include/rte_pflock.h @@ -179,6 +179,27 @@ rte_pflock_write_unlock(rte_pflock_t *pf) rte_atomic_fetch_add_explicit(&pf->wr.out, 1, rte_memory_order_release); } +/** + * Release a pflock held for writing, while keeping lock for reading. + * + * @param pf + * A pointer to a pflock structure. + */ +static inline void +rte_pflock_write_downgrade(rte_pflock_t *pf) +{ + /* Migrate from write phase to read phase. */ + rte_atomic_fetch_add_explicit(&pf->rd.in, RTE_PFLOCK_RINC, + rte_memory_order_acq_rel); + rte_atomic_fetch_and_explicit(&pf->rd.in, RTE_PFLOCK_LSB, + rte_memory_order_release); + + /* Allow other writers to continue. */ + rte_atomic_fetch_add_explicit(&pf->wr.out, 1, + rte_memory_order_release); +} + + #ifdef __cplusplus } #endif -- 2.51.0
