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padata: Convert from atomic_t to refcount_t on parallel_data->refcnt

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refcount_t type and corresponding API can protect refcounters from
accidental underflow and overflow and further use-after-free situations.

Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
Acked-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Xiyu Yang 2021-07-20 11:05:11 -04:00 committed by Herbert Xu
parent 192b722f38
commit d5ee8e750c
2 changed files with 6 additions and 5 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

3
include/linux/padata.h
View file

@ -12,6 +12,7 @@
#ifndef PADATA_H
#define PADATA_H
#include <linux/refcount.h>
#include <linux/compiler_types.h>
#include <linux/workqueue.h>
#include <linux/spinlock.h>
@ -96,7 +97,7 @@ struct parallel_data {
struct padata_shell *ps;
struct padata_list __percpu *reorder_list;
struct padata_serial_queue __percpu *squeue;
atomic_t refcnt;
refcount_t refcnt;
unsigned int seq_nr;
unsigned int processed;
int cpu;

8
kernel/padata.c
View file

@ -211,7 +211,7 @@ int padata_do_parallel(struct padata_shell *ps,
if ((pinst->flags & PADATA_RESET))
goto out;
atomic_inc(&pd->refcnt);
refcount_inc(&pd->refcnt);
padata->pd = pd;
padata->cb_cpu = *cb_cpu;
@ -383,7 +383,7 @@ static void padata_serial_worker(struct work_struct *serial_work)
}
local_bh_enable();
if (atomic_sub_and_test(cnt, &pd->refcnt))
if (refcount_sub_and_test(cnt, &pd->refcnt))
padata_free_pd(pd);
}
@ -593,7 +593,7 @@ static struct parallel_data *padata_alloc_pd(struct padata_shell *ps)
padata_init_reorder_list(pd);
padata_init_squeues(pd);
pd->seq_nr = -1;
atomic_set(&pd->refcnt, 1);
refcount_set(&pd->refcnt, 1);
spin_lock_init(&pd->lock);
pd->cpu = cpumask_first(pd->cpumask.pcpu);
INIT_WORK(&pd->reorder_work, invoke_padata_reorder);
@ -667,7 +667,7 @@ static int padata_replace(struct padata_instance *pinst)
synchronize_rcu();
list_for_each_entry_continue_reverse(ps, &pinst->pslist, list)
if (atomic_dec_and_test(&ps->opd->refcnt))
if (refcount_dec_and_test(&ps->opd->refcnt))
padata_free_pd(ps->opd);
pinst->flags &= ~PADATA_RESET;