[PATCH net-next v3 2/7] mld: get rid of inet6_dev->mc_lock

Taehee Yoo
2021-03-25T16:18:09Z

The purpose of mc_lock is to protect inet6_dev->mc_tomb.
But mc_tomb is already protected by RTNL and all functions,
which manipulate mc_tomb are called under RTNL.
So, mc_lock is not needed.
Furthermore, it is spinlock so the critical section is atomic.
In order to reduce atomic context, it should be removed.

Suggested-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
---
v2 -> v3:
- No change
v1 -> v2:
- Separated from previous big one patch.

include/net/if_inet6.h | 1 -
net/ipv6/mcast.c | 9 ---------
2 files changed, 10 deletions(-)

diff --git a/include/net/if_inet6.h b/include/net/if_inet6.h
index af5244c9ca5c..1080d2248304 100644
--- a/include/net/if_inet6.h
+++ b/include/net/if_inet6.h
@@ -167,7 +167,6 @@ struct inet6_dev {

struct ifmcaddr6 *mc_list;
struct ifmcaddr6 *mc_tomb;
- spinlock_t mc_lock;

unsigned char mc_qrv; /* Query Robustness Variable */
unsigned char mc_gq_running;
diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index 692a6dec8959..35962aa3cc22 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -752,10 +752,8 @@ static void mld_add_delrec(struct inet6_dev *idev, struct ifmcaddr6 *im)
}
spin_unlock_bh(&im->mca_lock);

- spin_lock_bh(&idev->mc_lock);
pmc->next = idev->mc_tomb;
idev->mc_tomb = pmc;
- spin_unlock_bh(&idev->mc_lock);
}

static void mld_del_delrec(struct inet6_dev *idev, struct ifmcaddr6 *im)
@@ -764,7 +762,6 @@ static void mld_del_delrec(struct inet6_dev *idev, struct ifmcaddr6 *im)
struct ip6_sf_list *psf;
struct in6_addr *pmca = &im->mca_addr;

- spin_lock_bh(&idev->mc_lock);
pmc_prev = NULL;
for (pmc = idev->mc_tomb; pmc; pmc = pmc->next) {
if (ipv6_addr_equal(&pmc->mca_addr, pmca))
@@ -777,7 +774,6 @@ static void mld_del_delrec(struct inet6_dev *idev, struct ifmcaddr6 *im)
else
idev->mc_tomb = pmc->next;
}
- spin_unlock_bh(&idev->mc_lock);

spin_lock_bh(&im->mca_lock);
if (pmc) {
@@ -801,10 +797,8 @@ static void mld_clear_delrec(struct inet6_dev *idev)
{
struct ifmcaddr6 *pmc, *nextpmc;

- spin_lock_bh(&idev->mc_lock);
pmc = idev->mc_tomb;
idev->mc_tomb = NULL;
- spin_unlock_bh(&idev->mc_lock);

for (; pmc; pmc = nextpmc) {
nextpmc = pmc->next;
@@ -1907,7 +1901,6 @@ static void mld_send_cr(struct inet6_dev *idev)
int type, dtype;

read_lock_bh(&idev->lock);
- spin_lock(&idev->mc_lock);

/* deleted MCA's */
pmc_prev = NULL;
@@ -1941,7 +1934,6 @@ static void mld_send_cr(struct inet6_dev *idev)
} else
pmc_prev = pmc;
}
- spin_unlock(&idev->mc_lock);

/* change recs */
for (pmc = idev->mc_list; pmc; pmc = pmc->next) {
@@ -2582,7 +2574,6 @@ void ipv6_mc_up(struct inet6_dev *idev)
void ipv6_mc_init_dev(struct inet6_dev *idev)
{
write_lock_bh(&idev->lock);
- spin_lock_init(&idev->mc_lock);
idev->mc_gq_running = 0;
INIT_DELAYED_WORK(&idev->mc_gq_work, mld_gq_work);
idev->mc_tomb = NULL;
--
2.17.1