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Subject[PATCH CSDlock 3/4] locking/csd_lock: Remove per-CPU data indirection from CSD lock debugging
Date
The diagnostics added by this commit were extremely useful in one instance:

a5aabace5fb8 ("locking/csd_lock: Add more data to CSD lock debugging")

However, they have not seen much action since, and there have been some
concerns expressed that the complexity is not worth the benefit.

Therefore, manually revert the following commit preparatory commit:

de7b09ef658d ("locking/csd_lock: Prepare more CSD lock debugging")

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Juergen Gross <jgross@suse.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
---
kernel/smp.c | 16 ++++++----------
1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/kernel/smp.c b/kernel/smp.c
index 038d666f327b..7a85bcddd9dc 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -31,12 +31,8 @@

#define CSD_TYPE(_csd) ((_csd)->node.u_flags & CSD_FLAG_TYPE_MASK)

-struct cfd_percpu {
- call_single_data_t csd;
-};
-
struct call_function_data {
- struct cfd_percpu __percpu *pcpu;
+ call_single_data_t __percpu *csd;
cpumask_var_t cpumask;
cpumask_var_t cpumask_ipi;
};
@@ -59,8 +55,8 @@ int smpcfd_prepare_cpu(unsigned int cpu)
free_cpumask_var(cfd->cpumask);
return -ENOMEM;
}
- cfd->pcpu = alloc_percpu(struct cfd_percpu);
- if (!cfd->pcpu) {
+ cfd->csd = alloc_percpu(call_single_data_t);
+ if (!cfd->csd) {
free_cpumask_var(cfd->cpumask);
free_cpumask_var(cfd->cpumask_ipi);
return -ENOMEM;
@@ -75,7 +71,7 @@ int smpcfd_dead_cpu(unsigned int cpu)

free_cpumask_var(cfd->cpumask);
free_cpumask_var(cfd->cpumask_ipi);
- free_percpu(cfd->pcpu);
+ free_percpu(cfd->csd);
return 0;
}

@@ -730,7 +726,7 @@ static void smp_call_function_many_cond(const struct cpumask *mask,

cpumask_clear(cfd->cpumask_ipi);
for_each_cpu(cpu, cfd->cpumask) {
- call_single_data_t *csd = &per_cpu_ptr(cfd->pcpu, cpu)->csd;
+ call_single_data_t *csd = per_cpu_ptr(cfd->csd, cpu);

if (cond_func && !cond_func(cpu, info))
continue;
@@ -774,7 +770,7 @@ static void smp_call_function_many_cond(const struct cpumask *mask,
for_each_cpu(cpu, cfd->cpumask) {
call_single_data_t *csd;

- csd = &per_cpu_ptr(cfd->pcpu, cpu)->csd;
+ csd = per_cpu_ptr(cfd->csd, cpu);
csd_lock_wait(csd);
}
}
--
2.40.0.rc2
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