spi: spi-geni-qcom: Fail new xfers if xfer/cancel/abort pending - linux-dev - Linux kernel development work

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author	Douglas Anderson <dianders@chromium.org>	2020-12-17 14:29:12 -0800
committer	Mark Brown <broonie@kernel.org>	2020-12-18 17:42:15 +0000
commit	690d8b917bbe64772cb0b652311bcd50908aea6b (patch)
tree	7d61a16d967026d4839b4da779d82268d20d4822 /Documentation/dev-tools/kunit/api/ssh:/git:
parent	spi: spi-geni-qcom: Fix geni_spi_isr() NULL dereference in timeout case (diff)

spi: spi-geni-qcom: Fail new xfers if xfer/cancel/abort pending

If we got a timeout when trying to send an abort command then it means that we just got 3 timeouts in a row: 1. The original timeout that caused handle_fifo_timeout() to be called. 2. A one second timeout waiting for the cancel command to finish. 3. A one second timeout waiting for the abort command to finish. SPI is clocked by the controller, so nothing (aside from a hardware fault or a totally broken sequencer) should be causing the actual commands to fail in hardware. However, even though the hardware itself is not expected to fail (and it'd be hard to predict how we should handle things if it did), it's easy to hit the timeout case by simply blocking our interrupt handler from running for a long period of time. Obviously the system is in pretty bad shape if a interrupt handler is blocked for > 2 seconds, but there are certainly bugs (even bugs in other unrelated drivers) that can make this happen. Let's make things a bit more robust against this case. If we fail to abort we'll set a flag and then we'll block all future transfers until we have no more interrupts pending. Fixes: 561de45f72bd ("spi: spi-geni-qcom: Add SPI driver support for GENI based QUP") Signed-off-by: Douglas Anderson <dianders@chromium.org> Reviewed-by: Stephen Boyd <swboyd@chromium.org> Link: https://lore.kernel.org/r/20201217142842.v3.2.Ibade998ed587e070388b4bf58801f1107a40eb53@changeid Signed-off-by: Mark Brown <broonie@kernel.org>

Diffstat (limited to 'Documentation/dev-tools/kunit/api/ssh:/git:')

0 files changed, 0 insertions, 0 deletions

// SPDX-License-Identifier: GPL-2.0-only /* * INET An implementation of the TCP/IP protocol suite for the LINUX * operating system. INET is implemented using the BSD Socket * interface as the means of communication with the user level. * * Generic TIME_WAIT sockets functions * * From code orinally in TCP */ #include <linux/kernel.h> #include <linux/slab.h> #include <linux/module.h> #include <net/inet_hashtables.h> #include <net/inet_timewait_sock.h> #include <net/ip.h> /** * inet_twsk_bind_unhash - unhash a timewait socket from bind hash * @tw: timewait socket * @hashinfo: hashinfo pointer * * unhash a timewait socket from bind hash, if hashed. * bind hash lock must be held by caller. * Returns 1 if caller should call inet_twsk_put() after lock release. */ void inet_twsk_bind_unhash(struct inet_timewait_sock *tw, struct inet_hashinfo *hashinfo) { struct inet_bind_bucket *tb = tw->tw_tb; if (!tb) return; __hlist_del(&tw->tw_bind_node); tw->tw_tb = NULL; inet_bind_bucket_destroy(hashinfo->bind_bucket_cachep, tb); __sock_put((struct sock *)tw); } /* Must be called with locally disabled BHs. */ static void inet_twsk_kill(struct inet_timewait_sock *tw) { struct inet_hashinfo *hashinfo = tw->tw_dr->hashinfo; spinlock_t *lock = inet_ehash_lockp(hashinfo, tw->tw_hash); struct inet_bind_hashbucket *bhead; spin_lock(lock); sk_nulls_del_node_init_rcu((struct sock *)tw); spin_unlock(lock); /* Disassociate with bind bucket. */ bhead = &hashinfo->bhash[inet_bhashfn(twsk_net(tw), tw->tw_num, hashinfo->bhash_size)]; spin_lock(&bhead->lock); inet_twsk_bind_unhash(tw, hashinfo); spin_unlock(&bhead->lock); atomic_dec(&tw->tw_dr->tw_count); inet_twsk_put(tw); } void inet_twsk_free(struct inet_timewait_sock *tw) { struct module *owner = tw->tw_prot->owner; twsk_destructor((struct sock *)tw); #ifdef SOCK_REFCNT_DEBUG pr_debug("%s timewait_sock %p released\n", tw->tw_prot->name, tw); #endif kmem_cache_free(tw->tw_prot->twsk_prot->twsk_slab, tw); module_put(owner); } void inet_twsk_put(struct inet_timewait_sock *tw) { if (refcount_dec_and_test(&tw->tw_refcnt)) inet_twsk_free(tw); } EXPORT_SYMBOL_GPL(inet_twsk_put); static void inet_twsk_add_node_rcu(struct inet_timewait_sock *tw, struct hlist_nulls_head *list) { hlist_nulls_add_head_rcu(&tw->tw_node, list); } static void inet_twsk_add_bind_node(struct inet_timewait_sock *tw, struct hlist_head *list) { hlist_add_head(&tw->tw_bind_node, list); } /* * Enter the time wait state. This is called with locally disabled BH. * Essentially we whip up a timewait bucket, copy the relevant info into it * from the SK, and mess with hash chains and list linkage. */ void inet_twsk_hashdance(struct inet_timewait_sock *tw, struct sock *sk, struct inet_hashinfo *hashinfo) { const struct inet_sock *inet = inet_sk(sk); const struct inet_connection_sock *icsk = inet_csk(sk); struct inet_ehash_bucket *ehead = inet_ehash_bucket(hashinfo, sk->sk_hash); spinlock_t *lock = inet_ehash_lockp(hashinfo, sk->sk_hash); struct inet_bind_hashbucket *bhead; /* Step 1: Put TW into bind hash. Original socket stays there too. Note, that any socket with inet->num != 0 MUST be bound in binding cache, even if it is closed. */ bhead = &hashinfo->bhash[inet_bhashfn(twsk_net(tw), inet->inet_num, hashinfo->bhash_size)]; spin_lock(&bhead->lock); tw->tw_tb = icsk->icsk_bind_hash; WARN_ON(!icsk->icsk_bind_hash); inet_twsk_add_bind_node(tw, &tw->tw_tb->owners); spin_unlock(&bhead->lock); spin_lock(lock); inet_twsk_add_node_rcu(tw, &ehead->chain); /* Step 3: Remove SK from hash chain */ if (__sk_nulls_del_node_init_rcu(sk)) sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1); spin_unlock(lock); /* tw_refcnt is set to 3 because we have : * - one reference for bhash chain. * - one reference for ehash chain. * - one reference for timer. * We can use atomic_set() because prior spin_lock()/spin_unlock() * committed into memory all tw fields. * Also note that after this point, we lost our implicit reference * so we are not allowed to use tw anymore. */ refcount_set(&tw->tw_refcnt, 3); } EXPORT_SYMBOL_GPL(inet_twsk_hashdance); static void tw_timer_handler(struct timer_list *t) { struct inet_timewait_sock *tw = from_timer(tw, t, tw_timer); if (tw->tw_kill) __NET_INC_STATS(twsk_net(tw), LINUX_MIB_TIMEWAITKILLED); else __NET_INC_STATS(twsk_net(tw), LINUX_MIB_TIMEWAITED); inet_twsk_kill(tw); } struct inet_timewait_sock *inet_twsk_alloc(const struct sock *sk, struct inet_timewait_death_row *dr, const int state) { struct inet_timewait_sock *tw; if (atomic_read(&dr->tw_count) >= dr->sysctl_max_tw_buckets) return NULL; tw = kmem_cache_alloc(sk->sk_prot_creator->twsk_prot->twsk_slab, GFP_ATOMIC); if (tw) { const struct inet_sock *inet = inet_sk(sk); tw->tw_dr = dr; /* Give us an identity. */ tw->tw_daddr = inet->inet_daddr; tw->tw_rcv_saddr = inet->inet_rcv_saddr; tw->tw_bound_dev_if = sk->sk_bound_dev_if; tw->tw_tos = inet->tos; tw->tw_num = inet->inet_num; tw->tw_state = TCP_TIME_WAIT; tw->tw_substate = state; tw->tw_sport = inet->inet_sport; tw->tw_dport = inet->inet_dport; tw->tw_family = sk->sk_family; tw->tw_reuse = sk->sk_reuse; tw->tw_reuseport = sk->sk_reuseport; tw->tw_hash = sk->sk_hash; tw->tw_ipv6only = 0; tw->tw_transparent = inet->transparent; tw->tw_prot = sk->sk_prot_creator; atomic64_set(&tw->tw_cookie, atomic64_read(&sk->sk_cookie)); twsk_net_set(tw, sock_net(sk)); timer_setup(&tw->tw_timer, tw_timer_handler, TIMER_PINNED); /* * Because we use RCU lookups, we should not set tw_refcnt * to a non null value before everything is setup for this * timewait socket. */ refcount_set(&tw->tw_refcnt, 0); __module_get(tw->tw_prot->owner); } return tw; } EXPORT_SYMBOL_GPL(inet_twsk_alloc); /* These are always called from BH context. See callers in * tcp_input.c to verify this. */ /* This is for handling early-kills of TIME_WAIT sockets. * Warning : consume reference. * Caller should not access tw anymore. */ void inet_twsk_deschedule_put(struct inet_timewait_sock *tw) { if (del_timer_sync(&tw->tw_timer)) inet_twsk_kill(tw); inet_twsk_put(tw); } EXPORT_SYMBOL(inet_twsk_deschedule_put); void __inet_twsk_schedule(struct inet_timewait_sock *tw, int timeo, bool rearm) { /* timeout := RTO * 3.5 * * 3.5 = 1+2+0.5 to wait for two retransmits. * * RATIONALE: if FIN arrived and we entered TIME-WAIT state, * our ACK acking that FIN can be lost. If N subsequent retransmitted * FINs (or previous seqments) are lost (probability of such event * is p^(N+1), where p is probability to lose single packet and * time to detect the loss is about RTO*(2^N - 1) with exponential * backoff). Normal timewait length is calculated so, that we * waited at least for one retransmitted FIN (maximal RTO is 120sec). * [ BTW Linux. following BSD, violates this requirement waiting * only for 60sec, we should wait at least for 240 secs. * Well, 240 consumes too much of resources 8) * ] * This interval is not reduced to catch old duplicate and * responces to our wandering segments living for two MSLs. * However, if we use PAWS to detect * old duplicates, we can reduce the interval to bounds required * by RTO, rather than MSL. So, if peer understands PAWS, we * kill tw bucket after 3.5*RTO (it is important that this number * is greater than TS tick!) and detect old duplicates with help * of PAWS. */ tw->tw_kill = timeo <= 4*HZ; if (!rearm) { BUG_ON(mod_timer(&tw->tw_timer, jiffies + timeo)); atomic_inc(&tw->tw_dr->tw_count); } else { mod_timer_pending(&tw->tw_timer, jiffies + timeo); } } EXPORT_SYMBOL_GPL(__inet_twsk_schedule); void inet_twsk_purge(struct inet_hashinfo *hashinfo, int family) { struct inet_timewait_sock *tw; struct sock *sk; struct hlist_nulls_node *node; unsigned int slot; for (slot = 0; slot <= hashinfo->ehash_mask; slot++) { struct inet_ehash_bucket *head = &hashinfo->ehash[slot]; restart_rcu: cond_resched(); rcu_read_lock(); restart: sk_nulls_for_each_rcu(sk, node, &head->chain) { if (sk->sk_state != TCP_TIME_WAIT) continue; tw = inet_twsk(sk); if ((tw->tw_family != family) || refcount_read(&twsk_net(tw)->count)) continue; if (unlikely(!refcount_inc_not_zero(&tw->tw_refcnt))) continue; if (unlikely((tw->tw_family != family) || refcount_read(&twsk_net(tw)->count))) { inet_twsk_put(tw); goto restart; } rcu_read_unlock(); local_bh_disable(); inet_twsk_deschedule_put(tw); local_bh_enable(); goto restart_rcu; } /* If the nulls value we got at the end of this lookup is * not the expected one, we must restart lookup. * We probably met an item that was moved to another chain. */ if (get_nulls_value(node) != slot) goto restart; rcu_read_unlock(); } } EXPORT_SYMBOL_GPL(inet_twsk_purge);


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