linux/kernel/rcu/refscale.c, branch v6.3

refscale: Add tests using SLAB_TYPESAFE_BY_RCU

2023-01-05T20:09:42Z

This commit adds three read-side-only tests of three use cases featuring SLAB_TYPESAFE_BY_RCU: One using per-object reference counting, one using per-object locking, and one using per-object sequence locking. [ paulmck: Apply feedback from kernel test robot. ] Signed-off-by: Paul E. McKenney

refscale: Provide for initialization failure

2023-01-04T01:52:54Z

Current tests all have init() functions that are guaranteed to succeed. But upcoming tests will need to allocate memory, thus possibly failing. This commit therefore handles init() function failure. Signed-off-by: Paul E. McKenney

refscale: Convert test_lock spinlock to raw_spinlock

2022-06-21T22:57:04Z

In kernels built with CONFIG_PREEMPT_RT=y, spinlocks are replaced by rt_mutex, which can sleep. This means that acquiring a non-raw spinlock in a critical section where preemption is disabled can trigger the following BUG: BUG: scheduling while atomic: ref_scale_reade/76/0x00000002 Preemption disabled at: ref_lock_section+0x16/0x80 Call Trace: dump_stack_lvl+0x5b/0x82 dump_stack+0x10/0x12 __schedule_bug.cold+0x9c/0xad __schedule+0x839/0xc00 schedule_rtlock+0x22/0x40 rtlock_slowlock_locked+0x460/0x1350 rt_spin_lock+0x61/0xe0 ref_lock_section+0x29/0x80 rcu_scale_one_reader+0x52/0x60 ref_scale_reader+0x28d/0x490 kthread+0x128/0x150 ret_from_fork+0x22/0x30 This commit therefore converts spinlock to raw_spinlock. Signed-off-by: Zqiang Signed-off-by: Paul E. McKenney

refscale: Allow refscale without RCU Tasks Rude/Trace

2022-04-20T23:53:19Z

Currently, a CONFIG_PREEMPT_NONE=y kernel substitutes normal RCU for RCU Tasks Rude and RCU Tasks Trace. Unless that kernel builds refscale, whether built-in or as a module, in which case these RCU Tasks flavors are (unnecessarily) built in. This both increases kernel size and increases the complexity of certain tracing operations. This commit therefore decouples the presence of refscale from the presence of RCU Tasks Rude and RCU Tasks Trace. Signed-off-by: Paul E. McKenney

refscale: Allow refscale without RCU Tasks

2022-04-20T23:53:19Z

Currently, a CONFIG_PREEMPT_NONE=y kernel substitutes normal RCU for RCU Tasks. Unless that kernel builds refscale, whether built-in or as a module, in which case RCU Tasks is (unnecessarily) built in. This both increases kernel size and increases the complexity of certain tracing operations. This commit therefore decouples the presence of refscale from the presence of RCU Tasks. Signed-off-by: Paul E. McKenney

refscale: Add missing '\n' to flush message

2021-12-08T00:36:12Z

Add '\n' to macros to flush message for each call. Acked-by: Davidlohr Bueso Signed-off-by: Li Zhijian Signed-off-by: Paul E. McKenney

refscale: Always log the error message

2021-12-08T00:31:44Z

An OOM is a serious error that should be logged even in non-verbose runs. This commit therefore adds an unconditional SCALEOUT_ERRSTRING() macro and uses it instead of VERBOSE_SCALEOUT_ERRSTRING() when reporting an OOM. [ paulmck: Drop do-while from SCALEOUT_ERRSTRING() due to only single statement. ] Signed-off-by: Li Zhijian Signed-off-by: Paul E. McKenney

refscale: Prevent buffer to pr_alert() being too long

2021-12-01T01:29:50Z

0Day/LKP observed that the refscale results fail to complete when larger values of nrun (such as 300) are specified. The problem is that printk() can accept at most a 1024-byte buffer. This commit therefore prints the buffer whenever its length exceeds 800 bytes. CC: Philip Li Reported-by: kernel test robot Signed-off-by: Li Zhijian Signed-off-by: Paul E. McKenney

refscale: Simplify the errexit checkpoint

2021-12-01T01:29:50Z

There is only the one OOM error case in main_func(), so this commit eliminates the errexit local variable in favor of a branch to cleanup code. Signed-off-by: Li Zhijian Signed-off-by: Paul E. McKenney

refscale: Warn on individual ref_scale_init() error conditions

2021-09-13T23:36:16Z

When running refscale as a module, any ref_scale_init() issues will be reflected in the error code from modprobe or insmod, as the case may be. However, these error codes are not available when running refscale built-in, for example, when using the kvm.sh script. This commit therefore adds WARN_ON_ONCE() to allow distinguishing ref_scale_init() errors when running refscale built-in. Signed-off-by: Paul E. McKenney