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Commit 8cbd9606 authored by Andy Grover's avatar Andy Grover Committed by David S. Miller
Browse files

RDS: Use spinlock to protect 64b value update on 32b archs 



We have a 64bit value that needs to be set atomically.
This is easy and quick on all 64bit archs, and can also be done
on x86/32 with set_64bit() (uses cmpxchg8b). However other
32b archs don't have this.

I actually changed this to the current state in preparation for
mainline because the old way (using a spinlock on 32b) resulted in
unsightly #ifdefs in the code. But obviously, being correct takes
precedence.

Signed-off-by: default avatarAndy Grover <andy.grover@oracle.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 745cbcca

net/rds/ib.h

+5 −9
Original line number Diff line number Diff line
@@ -108,7 +108,12 @@ struct rds_ib_connection { 


	/* sending acks */

	unsigned long		i_ack_flags;

#ifdef KERNEL_HAS_ATOMIC64

	atomic64_t		i_ack_next;	/* next ACK to send */

#else

	spinlock_t		i_ack_lock;	/* protect i_ack_next */

	u64			i_ack_next;	/* next ACK to send */

#endif

	struct rds_header	*i_ack;

	struct ib_send_wr	i_ack_wr;

	struct ib_sge		i_ack_sge;
@@ -363,13 +368,4 @@ rds_ib_data_sge(struct rds_ib_connection *ic, struct ib_sge *sge) 
	return &sge[1];

}



static inline void rds_ib_set_64bit(u64 *ptr, u64 val)

{

#if BITS_PER_LONG == 64

	*ptr = val;

#else

	set_64bit(ptr, val);

#endif

}



#endif

net/rds/ib_cm.c

+8 −1
Original line number Diff line number Diff line
@@ -636,7 +636,11 @@ void rds_ib_conn_shutdown(struct rds_connection *conn) 


	/* Clear the ACK state */

	clear_bit(IB_ACK_IN_FLIGHT, &ic->i_ack_flags);

	rds_ib_set_64bit(&ic->i_ack_next, 0);

#ifdef KERNEL_HAS_ATOMIC64

	atomic64_set(&ic->i_ack_next, 0);

#else

	ic->i_ack_next = 0;

#endif

	ic->i_ack_recv = 0;



	/* Clear flow control state */
@@ -669,6 +673,9 @@ int rds_ib_conn_alloc(struct rds_connection *conn, gfp_t gfp) 


	INIT_LIST_HEAD(&ic->ib_node);

	mutex_init(&ic->i_recv_mutex);

#ifndef KERNEL_HAS_ATOMIC64

	spin_lock_init(&ic->i_ack_lock);

#endif



	/*

	 * rds_ib_conn_shutdown() waits for these to be emptied so they

net/rds/ib_recv.c

+35 −2
Original line number Diff line number Diff line
@@ -395,10 +395,37 @@ void rds_ib_recv_init_ack(struct rds_ib_connection *ic) 
 * room for it beyond the ring size.  Send completion notices its special

 * wr_id and avoids working with the ring in that case.

 */

#ifndef KERNEL_HAS_ATOMIC64

static void rds_ib_set_ack(struct rds_ib_connection *ic, u64 seq,

				int ack_required)

{

	rds_ib_set_64bit(&ic->i_ack_next, seq);

	unsigned long flags;



	spin_lock_irqsave(&ic->i_ack_lock, flags);

	ic->i_ack_next = seq;

	if (ack_required)

		set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);

	spin_unlock_irqrestore(&ic->i_ack_lock, flags);

}



static u64 rds_ib_get_ack(struct rds_ib_connection *ic)

{

	unsigned long flags;

	u64 seq;



	clear_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);



	spin_lock_irqsave(&ic->i_ack_lock, flags);

	seq = ic->i_ack_next;

	spin_unlock_irqrestore(&ic->i_ack_lock, flags);



	return seq;

}

#else

static void rds_ib_set_ack(struct rds_ib_connection *ic, u64 seq,

				int ack_required)

{

	atomic64_set(&ic->i_ack_next, seq);

	if (ack_required) {

		smp_mb__before_clear_bit();

		set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
@@ -410,8 +437,10 @@ static u64 rds_ib_get_ack(struct rds_ib_connection *ic) 
	clear_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);

	smp_mb__after_clear_bit();



	return ic->i_ack_next;

	return atomic64_read(&ic->i_ack_next);

}

#endif





static void rds_ib_send_ack(struct rds_ib_connection *ic, unsigned int adv_credits)

{
@@ -464,6 +493,10 @@ static void rds_ib_send_ack(struct rds_ib_connection *ic, unsigned int adv_credi 
 *  -	i_ack_next, which is the last sequence number we received

 *

 * Potentially, send queue and receive queue handlers can run concurrently.

 * It would be nice to not have to use a spinlock to synchronize things,

 * but the one problem that rules this out is that 64bit updates are

 * not atomic on all platforms. Things would be a lot simpler if

 * we had atomic64 or maybe cmpxchg64 everywhere.

 *

 * Reconnecting complicates this picture just slightly. When we

 * reconnect, we may be seeing duplicate packets. The peer

net/rds/iw.h

+5 −9
Original line number Diff line number Diff line
@@ -131,7 +131,12 @@ struct rds_iw_connection { 


	/* sending acks */

	unsigned long		i_ack_flags;

#ifdef KERNEL_HAS_ATOMIC64

	atomic64_t		i_ack_next;	/* next ACK to send */

#else

	spinlock_t		i_ack_lock;	/* protect i_ack_next */

	u64			i_ack_next;	/* next ACK to send */

#endif

	struct rds_header	*i_ack;

	struct ib_send_wr	i_ack_wr;

	struct ib_sge		i_ack_sge;
@@ -391,13 +396,4 @@ rds_iw_data_sge(struct rds_iw_connection *ic, struct ib_sge *sge) 
	return &sge[1];

}



static inline void rds_iw_set_64bit(u64 *ptr, u64 val)

{

#if BITS_PER_LONG == 64

	*ptr = val;

#else

	set_64bit(ptr, val);

#endif

}



#endif

net/rds/iw_cm.c

+8 −1
Original line number Diff line number Diff line
@@ -659,7 +659,11 @@ void rds_iw_conn_shutdown(struct rds_connection *conn) 


	/* Clear the ACK state */

	clear_bit(IB_ACK_IN_FLIGHT, &ic->i_ack_flags);

	rds_iw_set_64bit(&ic->i_ack_next, 0);

#ifdef KERNEL_HAS_ATOMIC64

	atomic64_set(&ic->i_ack_next, 0);

#else

	ic->i_ack_next = 0;

#endif

	ic->i_ack_recv = 0;



	/* Clear flow control state */
@@ -693,6 +697,9 @@ int rds_iw_conn_alloc(struct rds_connection *conn, gfp_t gfp) 


	INIT_LIST_HEAD(&ic->iw_node);

	mutex_init(&ic->i_recv_mutex);

#ifndef KERNEL_HAS_ATOMIC64

	spin_lock_init(&ic->i_ack_lock);

#endif



	/*

	 * rds_iw_conn_shutdown() waits for these to be emptied so they