diff options
| author | Paul E. McKenney <paulmck@kernel.org> | 2024-11-11 16:28:51 -0800 |
|---|---|---|
| committer | Frederic Weisbecker <frederic@kernel.org> | 2024-11-15 22:13:37 +0100 |
| commit | 9407f5c3ec10c155aae61fc4496a7c17a96907b4 (patch) | |
| tree | 397052adc7965b385e628f13fd87862fa424a4b3 /include/linux/srcutiny.h | |
| parent | f8ce622ac9d89260595e26d4e0da8cb6b4a8e030 (diff) | |
srcu: Unconditionally record srcu_read_lock_lite() in ->srcu_reader_flavor
Currently, srcu_read_lock_lite() uses the SRCU_READ_FLAVOR_LITE bit in
->srcu_reader_flavor to communicate to the grace-period processing in
srcu_readers_active_idx_check() that the smp_mb() must be replaced by a
synchronize_rcu(). Unfortunately, ->srcu_reader_flavor is not updated
unless the kernel is built with CONFIG_PROVE_RCU=y. Therefore in all
kernels built with CONFIG_PROVE_RCU=n, srcu_readers_active_idx_check()
incorrectly uses smp_mb() instead of synchronize_rcu() for srcu_struct
structures whose readers use srcu_read_lock_lite().
This commit therefore causes Tree SRCU srcu_read_lock_lite()
to unconditionally update ->srcu_reader_flavor so that
srcu_readers_active_idx_check() can make the correct choice.
Reported-by: Neeraj Upadhyay <Neeraj.Upadhyay@amd.com>
Closes: https://lore.kernel.org/all/d07e8f4a-d5ff-4c8e-8e61-50db285c57e9@amd.com/
Fixes: c0f08d6b5a61 ("srcu: Add srcu_read_lock_lite() and srcu_read_unlock_lite()")
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Neeraj Upadhyay <Neeraj.Upadhyay@amd.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Diffstat (limited to 'include/linux/srcutiny.h')
| -rw-r--r-- | include/linux/srcutiny.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/include/linux/srcutiny.h b/include/linux/srcutiny.h index 4d96bbdb45f0..1321da803274 100644 --- a/include/linux/srcutiny.h +++ b/include/linux/srcutiny.h @@ -81,6 +81,9 @@ static inline void srcu_barrier(struct srcu_struct *ssp) synchronize_srcu(ssp); } +#define srcu_check_read_flavor(ssp, read_flavor) do { } while (0) +#define srcu_check_read_flavor_lite(ssp) do { } while (0) + /* Defined here to avoid size increase for non-torture kernels. */ static inline void srcu_torture_stats_print(struct srcu_struct *ssp, char *tt, char *tf) |