blaster4385/linux-IllusionX/kernel/rcu/refscale.c, branch v6.12.10

refscale: Constify struct ref_scale_ops

2024-08-14T18:44:48Z

'struct ref_scale_ops' are not modified in these drivers. Constifying this structure moves some data to a read-only section, so increase overall security. On a x86_64, with allmodconfig: Before: ====== text data bss dec hex filename 34231 4167 736 39134 98de kernel/rcu/refscale.o After: ===== text data bss dec hex filename 35175 3239 736 39150 98ee kernel/rcu/refscale.o Signed-off-by: Christophe JAILLET Tested-by: "Paul E. McKenney" Signed-off-by: Neeraj Upadhyay

refscale: Optimize process_durations()

2024-08-14T11:36:01Z

process_durations() is not a hot path, but there is no good reason to iterate over and over the data already in 'buf'. Using a seq_buf saves some useless strcat() and the need of a temp buffer. Data is written directly at the correct place. Signed-off-by: Christophe JAILLET Tested-by: "Paul E. McKenney" Reviewed-by: Davidlohr Bueso Signed-off-by: Neeraj Upadhyay

rcutorture: Add missing MODULE_DESCRIPTION() macros

2024-06-06T18:44:42Z

Fix the following 'make W=1' warnings: WARNING: modpost: missing MODULE_DESCRIPTION() in kernel/rcu/rcutorture.o WARNING: modpost: missing MODULE_DESCRIPTION() in kernel/rcu/rcuscale.o WARNING: modpost: missing MODULE_DESCRIPTION() in kernel/rcu/refscale.o Signed-off-by: Jeff Johnson Signed-off-by: Paul E. McKenney

refscale: Print out additional module parameters

2023-09-11T21:02:18Z

The refscale.verbose_batched and refscale.lookup_instances module parameters are omitted from the ref_scale_print_module_parms() beginning-of-test output. This commit therefore adds them. Signed-off-by: Paul E. McKenney Signed-off-by: Frederic Weisbecker

refscale: Fix misplaced data re-read

2023-09-11T21:00:32Z

This commit fixes a misplaced data re-read in the typesafe code. The reason that this was not noticed is that this is a performance test with no writers, so a mismatch could not occur. Signed-off-by: Paul E. McKenney Signed-off-by: Frederic Weisbecker

refscale: Add a "jiffies" test

2023-07-14T22:01:04Z

This commit adds a "jiffies" test to refscale, allowing use of jiffies to be compared to ktime_get_real_fast_ns(). On my x86 laptop, jiffies is more than 20x faster. (Though for many uses, the tens-of-nanoseconds overhead of ktime_get_real_fast_ns() will be just fine.) Signed-off-by: Paul E. McKenney

refscale: Fix uninitalized use of wait_queue_head_t

2023-07-14T22:01:04Z

Running the refscale test occasionally crashes the kernel with the following error: [ 8569.952896] BUG: unable to handle page fault for address: ffffffffffffffe8 [ 8569.952900] #PF: supervisor read access in kernel mode [ 8569.952902] #PF: error_code(0x0000) - not-present page [ 8569.952904] PGD c4b048067 P4D c4b049067 PUD c4b04b067 PMD 0 [ 8569.952910] Oops: 0000 [#1] PREEMPT_RT SMP NOPTI [ 8569.952916] Hardware name: Dell Inc. PowerEdge R750/0WMWCR, BIOS 1.2.4 05/28/2021 [ 8569.952917] RIP: 0010:prepare_to_wait_event+0x101/0x190 : [ 8569.952940] Call Trace: [ 8569.952941] [ 8569.952944] ref_scale_reader+0x380/0x4a0 [refscale] [ 8569.952959] kthread+0x10e/0x130 [ 8569.952966] ret_from_fork+0x1f/0x30 [ 8569.952973] The likely cause is that init_waitqueue_head() is called after the call to the torture_create_kthread() function that creates the ref_scale_reader kthread. Although this init_waitqueue_head() call will very likely complete before this kthread is created and starts running, it is possible that the calling kthread will be delayed between the calls to torture_create_kthread() and init_waitqueue_head(). In this case, the new kthread will use the waitqueue head before it is properly initialized, which is not good for the kernel's health and well-being. The above crash happened here: static inline void __add_wait_queue(...) { : if (!(wq->flags & WQ_FLAG_PRIORITY)) <=== Crash here The offset of flags from list_head entry in wait_queue_entry is -0x18. If reader_tasks[i].wq.head.next is NULL as allocated reader_task structure is zero initialized, the instruction will try to access address 0xffffffffffffffe8, which is exactly the fault address listed above. This commit therefore invokes init_waitqueue_head() before creating the kthread. Fixes: 653ed64b01dc ("refperf: Add a test to measure performance of read-side synchronization") Signed-off-by: Waiman Long Reviewed-by: Qiuxu Zhuo Reviewed-by: Davidlohr Bueso Acked-by: Joel Fernandes (Google) Signed-off-by: Paul E. McKenney

refscale: Move shutdown from wait_event() to wait_event_idle()

2023-03-20T18:12:16Z

The ref_scale_shutdown() kthread/function uses wait_event() to wait for the refscale test to complete. However, although the read-side tests are normally extremely fast, there is no law against specifying a very large value for the refscale.loops module parameter or against having a slow read-side primitive. Either way, this might well trigger the hung-task timeout. This commit therefore replaces those wait_event() calls with calls to wait_event_idle(), which do not trigger the hung-task timeout. Signed-off-by: Paul E. McKenney Signed-off-by: Boqun Feng

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