Skip to content
Permalink
Browse files
mld: convert ip6_sf_list to RCU 
The ip6_sf_list has been protected by mca_lock(spin_lock) so that the
critical section is atomic context. In order to switch this context,
changing locking is needed. The ip6_sf_list actually already protected
by RTNL So if it's converted to use RCU, its control path context can
be switched to sleepable.
But It doesn't remove mca_lock yet because ifmcaddr6 isn't converted
to RCU yet. So, It's not fully converted to the sleepable context.

Suggested-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
  • Loading branch information
@TaeheeYoo @intel-lab-lkp
TaeheeYoo authored and intel-lab-lkp committed Feb 13, 2021
1 parent 5a21fa3 commit 50d689e601cc17c3b2bf668b2e5be766e9dbc7b3
Show file tree
Hide file tree
Showing 2 changed files with 95 additions and 60 deletions.
5 include/net/if_inet6.h
View file
@@ -97,12 +97,13 @@ struct ipv6_mc_socklist {
};

struct ip6_sf_list {
struct ip6_sf_list *sf_next;
struct ip6_sf_list __rcu *sf_next;
struct in6_addr sf_addr;
unsigned long sf_count[2]; /* include/exclude counts */
unsigned char sf_gsresp; /* include in g & s response? */
unsigned char sf_oldin; /* change state */
unsigned char sf_crcount; /* retrans. left to send */
struct rcu_head rcu;
};

#define MAF_TIMER_RUNNING 0x01
@@ -113,7 +114,7 @@ struct ifmcaddr6 {
struct in6_addr mca_addr;
struct inet6_dev *idev;
struct ifmcaddr6 *next;
struct ip6_sf_list *mca_sources;
struct ip6_sf_list __rcu *mca_sources;
struct ip6_sf_list *mca_tomb;
unsigned int mca_sfmode;
unsigned char mca_crcount;
150 net/ipv6/mcast.c
View file
@@ -113,10 +113,20 @@ int sysctl_mld_qrv __read_mostly = MLD_QRV_DEFAULT;
*/

#define for_each_pmc_rcu(np, pmc) \
for (pmc = rcu_dereference(np->ipv6_mc_list); \
pmc != NULL; \
for (pmc = rcu_dereference((np)->ipv6_mc_list); \
pmc; \
pmc = rcu_dereference(pmc->next))

#define for_each_psf_rtnl(mc, psf) \
for (psf = rtnl_dereference((mc)->mca_sources); \
psf; \
psf = rtnl_dereference(psf->sf_next))

#define for_each_psf_rcu(mc, psf) \
for (psf = rcu_dereference((mc)->mca_sources); \
psf; \
psf = rcu_dereference(psf->sf_next))

static int unsolicited_report_interval(struct inet6_dev *idev)
{
int iv;
@@ -731,22 +741,25 @@ static void mld_add_delrec(struct inet6_dev *idev, struct ifmcaddr6 *im)
struct ip6_sf_list *psf;

pmc->mca_tomb = im->mca_tomb;
pmc->mca_sources = im->mca_sources;
im->mca_tomb = im->mca_sources = NULL;
for (psf = pmc->mca_sources; psf; psf = psf->sf_next)
rcu_assign_pointer(pmc->mca_sources,
rtnl_dereference(im->mca_sources));
im->mca_tomb = NULL;
RCU_INIT_POINTER(im->mca_sources, NULL);

for_each_psf_rtnl(pmc, psf)
psf->sf_crcount = pmc->mca_crcount;
}
spin_unlock_bh(&im->mca_lock);

pmc->next = idev->mc_tomb;
rcu_assign_pointer(pmc->next, idev->mc_tomb);
idev->mc_tomb = pmc;
}

static void mld_del_delrec(struct inet6_dev *idev, struct ifmcaddr6 *im)
{
struct ifmcaddr6 *pmc, *pmc_prev;
struct ip6_sf_list *psf;
struct in6_addr *pmca = &im->mca_addr;
struct ip6_sf_list *psf, *sources;
struct ifmcaddr6 *pmc, *pmc_prev;

pmc_prev = NULL;
for (pmc = idev->mc_tomb; pmc; pmc = pmc->next) {
@@ -766,8 +779,12 @@ static void mld_del_delrec(struct inet6_dev *idev, struct ifmcaddr6 *im)
im->idev = pmc->idev;
if (im->mca_sfmode == MCAST_INCLUDE) {
swap(im->mca_tomb, pmc->mca_tomb);
swap(im->mca_sources, pmc->mca_sources);
for (psf = im->mca_sources; psf; psf = psf->sf_next)

sources = rcu_replace_pointer(im->mca_sources,
pmc->mca_sources,
lockdep_rtnl_is_held());
rcu_assign_pointer(pmc->mca_sources, sources);
for_each_psf_rtnl(im, psf)
psf->sf_crcount = idev->mc_qrv;
} else {
im->mca_crcount = idev->mc_qrv;
@@ -803,8 +820,8 @@ static void mld_clear_delrec(struct inet6_dev *idev)
pmc->mca_tomb = NULL;
spin_unlock_bh(&pmc->mca_lock);
for (; psf; psf = psf_next) {
psf_next = psf->sf_next;
kfree(psf);
psf_next = rtnl_dereference(psf->sf_next);
kfree_rcu(psf, rcu);
}
}
read_unlock_bh(&idev->lock);
@@ -986,7 +1003,7 @@ bool ipv6_chk_mcast_addr(struct net_device *dev, const struct in6_addr *group,
struct ip6_sf_list *psf;

spin_lock_bh(&mc->mca_lock);
for (psf = mc->mca_sources; psf; psf = psf->sf_next) {
for_each_psf_rcu(mc, psf) {
if (ipv6_addr_equal(&psf->sf_addr, src_addr))
break;
}
@@ -1101,7 +1118,7 @@ static bool mld_xmarksources(struct ifmcaddr6 *pmc, int nsrcs,
int i, scount;

scount = 0;
for (psf = pmc->mca_sources; psf; psf = psf->sf_next) {
for_each_psf_rcu(pmc, psf) {
if (scount == nsrcs)
break;
for (i = 0; i < nsrcs; i++) {
@@ -1134,7 +1151,7 @@ static bool mld_marksources(struct ifmcaddr6 *pmc, int nsrcs,
/* mark INCLUDE-mode sources */

scount = 0;
for (psf = pmc->mca_sources; psf; psf = psf->sf_next) {
for_each_psf_rcu(pmc, psf) {
if (scount == nsrcs)
break;
for (i = 0; i < nsrcs; i++) {
@@ -1544,7 +1561,7 @@ mld_scount(struct ifmcaddr6 *pmc, int type, int gdeleted, int sdeleted)
struct ip6_sf_list *psf;
int scount = 0;

for (psf = pmc->mca_sources; psf; psf = psf->sf_next) {
for_each_psf_rtnl(pmc, psf) {
if (!is_in(pmc, psf, type, gdeleted, sdeleted))
continue;
scount++;
@@ -1719,14 +1736,16 @@ static struct sk_buff *add_grhead(struct sk_buff *skb, struct ifmcaddr6 *pmc,
#define AVAILABLE(skb) ((skb) ? skb_availroom(skb) : 0)

static struct sk_buff *add_grec(struct sk_buff *skb, struct ifmcaddr6 *pmc,
int type, int gdeleted, int sdeleted, int crsend)
int type, int gdeleted, int sdeleted,
int crsend)
{
int scount, stotal, first, isquery, truncate;
struct ip6_sf_list __rcu **psf_list;
struct ip6_sf_list *psf, *psf_prev;
struct inet6_dev *idev = pmc->idev;
struct net_device *dev = idev->dev;
struct mld2_report *pmr;
struct mld2_grec *pgr = NULL;
struct ip6_sf_list *psf, *psf_next, *psf_prev, **psf_list;
int scount, stotal, first, isquery, truncate;
struct mld2_report *pmr;
unsigned int mtu;

if (pmc->mca_noreport)
@@ -1743,10 +1762,13 @@ static struct sk_buff *add_grec(struct sk_buff *skb, struct ifmcaddr6 *pmc,

stotal = scount = 0;

psf_list = sdeleted ? &pmc->mca_tomb : &pmc->mca_sources;

if (!*psf_list)
goto empty_source;
if (sdeleted) {
if (!pmc->mca_tomb)
goto empty_source;
} else {
if (!rcu_access_pointer(pmc->mca_sources))
goto empty_source;
}

pmr = skb ? (struct mld2_report *)skb_transport_header(skb) : NULL;

@@ -1761,10 +1783,12 @@ static struct sk_buff *add_grec(struct sk_buff *skb, struct ifmcaddr6 *pmc,
}
first = 1;
psf_prev = NULL;
for (psf = *psf_list; psf; psf = psf_next) {
for (psf_list = &pmc->mca_sources;
(psf = rtnl_dereference(*psf_list)) != NULL;
psf_list = &psf->sf_next) {
struct in6_addr *psrc;

psf_next = psf->sf_next;
*psf_list = rtnl_dereference(psf->sf_next);

if (!is_in(pmc, psf, type, gdeleted, sdeleted) && !crsend) {
psf_prev = psf;
@@ -1811,10 +1835,11 @@ static struct sk_buff *add_grec(struct sk_buff *skb, struct ifmcaddr6 *pmc,
psf->sf_crcount--;
if ((sdeleted || gdeleted) && psf->sf_crcount == 0) {
if (psf_prev)
psf_prev->sf_next = psf->sf_next;
rcu_assign_pointer(psf_prev->sf_next,
rtnl_dereference(psf->sf_next));
else
*psf_list = psf->sf_next;
kfree(psf);
*psf_list = rtnl_dereference(psf->sf_next);
kfree_rcu(psf, rcu);
continue;
}
}
@@ -1883,16 +1908,18 @@ static void mld_clear_zeros(struct ip6_sf_list **ppsf)
struct ip6_sf_list *psf_prev, *psf_next, *psf;

psf_prev = NULL;
for (psf = *ppsf; psf; psf = psf_next) {
psf_next = psf->sf_next;
for (psf = rtnl_dereference(*ppsf); psf; psf = psf_next) {
psf_next = rtnl_dereference(psf->sf_next);
if (psf->sf_crcount == 0) {
if (psf_prev)
psf_prev->sf_next = psf->sf_next;
rcu_assign_pointer(psf_prev->sf_next,
rtnl_dereference(psf->sf_next));
else
*ppsf = psf->sf_next;
kfree(psf);
} else
*ppsf = rtnl_dereference(psf->sf_next);
kfree_rcu(psf, rcu);
} else {
psf_prev = psf;
}
}
}

@@ -2137,7 +2164,7 @@ static int ip6_mc_del1_src(struct ifmcaddr6 *pmc, int sfmode,
int rv = 0;

psf_prev = NULL;
for (psf = pmc->mca_sources; psf; psf = psf->sf_next) {
for_each_psf_rtnl(pmc, psf) {
if (ipv6_addr_equal(&psf->sf_addr, psfsrc))
break;
psf_prev = psf;
@@ -2152,17 +2179,20 @@ static int ip6_mc_del1_src(struct ifmcaddr6 *pmc, int sfmode,

/* no more filters for this source */
if (psf_prev)
psf_prev->sf_next = psf->sf_next;
rcu_assign_pointer(psf_prev->sf_next,
rtnl_dereference(psf->sf_next));
else
pmc->mca_sources = psf->sf_next;
rcu_assign_pointer(pmc->mca_sources,
rtnl_dereference(psf->sf_next));
if (psf->sf_oldin && !pmc->mca_noreport &&
!mld_in_v1_mode(idev)) {
psf->sf_crcount = idev->mc_qrv;
psf->sf_next = pmc->mca_tomb;
rcu_assign_pointer(psf->sf_next, pmc->mca_tomb);
pmc->mca_tomb = psf;
rv = 1;
} else
kfree(psf);
} else {
kfree_rcu(psf, rcu);
}
}
return rv;
}
@@ -2214,7 +2244,7 @@ static int ip6_mc_del_src(struct inet6_dev *idev, const struct in6_addr *pmca,
pmc->mca_sfmode = MCAST_INCLUDE;
pmc->mca_crcount = idev->mc_qrv;
idev->mc_ifc_count = pmc->mca_crcount;
for (psf = pmc->mca_sources; psf; psf = psf->sf_next)
for_each_psf_rtnl(pmc, psf)
psf->sf_crcount = 0;
mld_ifc_event(pmc->idev);
} else if (sf_setstate(pmc) || changerec)
@@ -2233,7 +2263,7 @@ static int ip6_mc_add1_src(struct ifmcaddr6 *pmc, int sfmode,
struct ip6_sf_list *psf, *psf_prev;

psf_prev = NULL;
for (psf = pmc->mca_sources; psf; psf = psf->sf_next) {
for_each_psf_rtnl(pmc, psf) {
if (ipv6_addr_equal(&psf->sf_addr, psfsrc))
break;
psf_prev = psf;
@@ -2245,9 +2275,10 @@ static int ip6_mc_add1_src(struct ifmcaddr6 *pmc, int sfmode,

psf->sf_addr = *psfsrc;
if (psf_prev) {
psf_prev->sf_next = psf;
} else
pmc->mca_sources = psf;
rcu_assign_pointer(psf_prev->sf_next, psf);
} else {
rcu_assign_pointer(pmc->mca_sources, psf);
}
}
psf->sf_count[sfmode]++;
return 0;
@@ -2258,13 +2289,15 @@ static void sf_markstate(struct ifmcaddr6 *pmc)
struct ip6_sf_list *psf;
int mca_xcount = pmc->mca_sfcount[MCAST_EXCLUDE];

for (psf = pmc->mca_sources; psf; psf = psf->sf_next)
for_each_psf_rtnl(pmc, psf) {
if (pmc->mca_sfcount[MCAST_EXCLUDE]) {
psf->sf_oldin = mca_xcount ==
psf->sf_count[MCAST_EXCLUDE] &&
!psf->sf_count[MCAST_INCLUDE];
} else
} else {
psf->sf_oldin = psf->sf_count[MCAST_INCLUDE] != 0;
}
}
}

static int sf_setstate(struct ifmcaddr6 *pmc)
@@ -2275,7 +2308,7 @@ static int sf_setstate(struct ifmcaddr6 *pmc)
int new_in, rv;

rv = 0;
for (psf = pmc->mca_sources; psf; psf = psf->sf_next) {
for_each_psf_rtnl(pmc, psf) {
if (pmc->mca_sfcount[MCAST_EXCLUDE]) {
new_in = mca_xcount == psf->sf_count[MCAST_EXCLUDE] &&
!psf->sf_count[MCAST_INCLUDE];
@@ -2317,7 +2350,6 @@ static int sf_setstate(struct ifmcaddr6 *pmc)
if (!dpsf)
continue;
*dpsf = *psf;
/* pmc->mca_lock held by callers */
dpsf->sf_next = pmc->mca_tomb;
pmc->mca_tomb = dpsf;
}
@@ -2382,7 +2414,7 @@ static int ip6_mc_add_src(struct inet6_dev *idev, const struct in6_addr *pmca,

pmc->mca_crcount = idev->mc_qrv;
idev->mc_ifc_count = pmc->mca_crcount;
for (psf = pmc->mca_sources; psf; psf = psf->sf_next)
for_each_psf_rtnl(pmc, psf)
psf->sf_crcount = 0;
mld_ifc_event(idev);
} else if (sf_setstate(pmc))
@@ -2401,11 +2433,13 @@ static void ip6_mc_clear_src(struct ifmcaddr6 *pmc)
kfree(psf);
}
pmc->mca_tomb = NULL;
for (psf = pmc->mca_sources; psf; psf = nextpsf) {
nextpsf = psf->sf_next;
kfree(psf);
for (psf = rtnl_dereference(pmc->mca_sources);
psf;
psf = nextpsf) {
nextpsf = rtnl_dereference(psf->sf_next);
kfree_rcu(psf, rcu);
}
pmc->mca_sources = NULL;
RCU_INIT_POINTER(pmc->mca_sources, NULL);
pmc->mca_sfmode = MCAST_EXCLUDE;
pmc->mca_sfcount[MCAST_INCLUDE] = 0;
pmc->mca_sfcount[MCAST_EXCLUDE] = 1;
@@ -2823,7 +2857,7 @@ static inline struct ip6_sf_list *igmp6_mcf_get_first(struct seq_file *seq)
im = idev->mc_list;
if (likely(im)) {
spin_lock_bh(&im->mca_lock);
psf = im->mca_sources;
psf = rcu_dereference(im->mca_sources);
if (likely(psf)) {
state->im = im;
state->idev = idev;
@@ -2840,7 +2874,7 @@ static struct ip6_sf_list *igmp6_mcf_get_next(struct seq_file *seq, struct ip6_s
{
struct igmp6_mcf_iter_state *state = igmp6_mcf_seq_private(seq);

psf = psf->sf_next;
psf = rcu_dereference(psf->sf_next);
while (!psf) {
spin_unlock_bh(&state->im->mca_lock);
state->im = state->im->next;
@@ -2862,7 +2896,7 @@ static struct ip6_sf_list *igmp6_mcf_get_next(struct seq_file *seq, struct ip6_s
if (!state->im)
break;
spin_lock_bh(&state->im->mca_lock);
psf = state->im->mca_sources;
psf = rcu_dereference(state->im->mca_sources);
}
out:
return psf;

0 comments on commit 50d689e

Please sign in to comment.