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srcu: Use static init for statically allocated in-module srcu_struct

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Further shrinking the srcu_struct structure is eased by requiring
that in-module srcu_struct structures rely more heavily on static
initialization.  In particular, this preserves the property that
a module-load-time srcu_struct initialization can fail only due
to memory-allocation failure of the per-CPU srcu_data structures.
It might also slightly improve robustness by keeping the number of memory
allocations that must succeed down percpu_alloc() call.

This is in preparation for splitting an srcu_usage structure out
of the srcu_struct structure.

[ paulmck: Fold in qiang1.zhang@intel.com feedback. ]

Cc: Christoph Hellwig <hch@lst.de>
Tested-by: Sachin Sant <sachinp@linux.ibm.com>
Tested-by: "Zhang, Qiang1" <qiang1.zhang@intel.com>
Tested-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
Paul E. McKenney
2023-03-17 13:28:04 -07:00
parent 3e67cb8a3c
commit f4d01a2593
2 changed files with 27 additions and 11 deletions
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19
kernel/rcu/srcutree.c
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@@ -1873,13 +1873,14 @@ void __init srcu_init(void)
static int srcu_module_coming(struct module *mod)
{
int i;
struct srcu_struct *ssp;
struct srcu_struct **sspp = mod->srcu_struct_ptrs;
int ret;
for (i = 0; i < mod->num_srcu_structs; i++) {
ret = init_srcu_struct(*(sspp++));
if (WARN_ON_ONCE(ret))
return ret;
ssp = *(sspp++);
ssp->sda = alloc_percpu(struct srcu_data);
if (WARN_ON_ONCE(!ssp->sda))
return -ENOMEM;
}
return 0;
}
@@ -1888,10 +1889,16 @@ static int srcu_module_coming(struct module *mod)
static void srcu_module_going(struct module *mod)
{
int i;
struct srcu_struct *ssp;
struct srcu_struct **sspp = mod->srcu_struct_ptrs;
for (i = 0; i < mod->num_srcu_structs; i++)
cleanup_srcu_struct(*(sspp++));
for (i = 0; i < mod->num_srcu_structs; i++) {
ssp = *(sspp++);
if (!rcu_seq_state(smp_load_acquire(&ssp->srcu_gp_seq_needed)) &&
!WARN_ON_ONCE(!ssp->sda_is_static))
cleanup_srcu_struct(ssp);
free_percpu(ssp->sda);
}
}
/* Handle one module, either coming or going. */