[PATCH net-next 0/6] s390/ctcm: updates 2020-11-30

[PATCH net-next 0/6] s390/ctcm: updates 2020-11-30

[Julian Wiedmann]

Hi Jakub,

please apply the following patch series for ctcm to netdev's net-next tree.

Some rare ctcm updates by Sebastian, who cleans up all places where
in_interrupt() was used to determine the correct GFP_* mask for
allocations.
In the first three patches we can get rid of those allocations entirely,
as they just end up being copied into the skb.

Thanks,
Julian

Sebastian Andrzej Siewior (6):
  s390/ctcm: Avoid temporary allocation of struct th_header and
    th_sweep.
  s390/ctcm: Avoid temporary allocation of struct qllc.
  s390/ctcm: Avoid temporary allocation of struct pdu.
  s390/ctcm: Use explicit allocation mask in ctcmpc_unpack_skb().
  s390/ctcm: Use GFP_KERNEL in add_channel().
  s390/ctcm: Use GFP_ATOMIC in ctcmpc_tx().

 drivers/s390/net/ctcm_fsms.c | 15 +++-----
 drivers/s390/net/ctcm_main.c | 68 ++++++++----------------------------
 drivers/s390/net/ctcm_main.h |  5 ---
 drivers/s390/net/ctcm_mpc.c  | 39 ++++-----------------
 4 files changed, 24 insertions(+), 103 deletions(-)

-- 
2.17.1

[PATCH net-next 1/6] s390/ctcm: Avoid temporary allocation of struct th_header and th_sweep.

[Julian Wiedmann]

From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

The size of struct th_header is 8 byte and the size of struct th_sweep
is 16 byte. The memory for is allocated, initialized, used and
deallocated a few lines later.

It is more efficient to avoid the allocation/free dance and assign the
values directly to skb's data part instead of using memcpy() for it.

Avoid an allocation of struct th_sweep/th_header and use the resulting
skb pointer instead.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
[jwi: use skb_put_zero(), instead of skb_put() + memset to 0]
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
---
 drivers/s390/net/ctcm_fsms.c | 15 ++++-----------
 drivers/s390/net/ctcm_main.c | 31 ++++---------------------------
 drivers/s390/net/ctcm_mpc.c  | 16 +---------------
 3 files changed, 9 insertions(+), 53 deletions(-)

diff --git a/drivers/s390/net/ctcm_fsms.c b/drivers/s390/net/ctcm_fsms.c
index 661d2a49bce9..b341075397d9 100644
--- a/drivers/s390/net/ctcm_fsms.c
+++ b/drivers/s390/net/ctcm_fsms.c
@@ -1303,12 +1303,10 @@ static void ctcmpc_chx_txdone(fsm_instance *fi, int event, void *arg)
 	/* p_header points to the last one we handled */
 	if (p_header)
 		p_header->pdu_flag |= PDU_LAST;	/*Say it's the last one*/
-	header = kzalloc(TH_HEADER_LENGTH, gfp_type());
-	if (!header) {
-		spin_unlock(&ch->collect_lock);
-		fsm_event(priv->mpcg->fsm, MPCG_EVENT_INOP, dev);
-				goto done;
-	}
+
+	header = skb_push(ch->trans_skb, TH_HEADER_LENGTH);
+	memset(header, 0, TH_HEADER_LENGTH);
+
 	header->th_ch_flag = TH_HAS_PDU;  /* Normal data */
 	ch->th_seq_num++;
 	header->th_seq_num = ch->th_seq_num;
@@ -1316,11 +1314,6 @@ static void ctcmpc_chx_txdone(fsm_instance *fi, int event, void *arg)
 	CTCM_PR_DBGDATA("%s: ToVTAM_th_seq= %08x\n" ,
 					__func__, ch->th_seq_num);
 
-	memcpy(skb_push(ch->trans_skb, TH_HEADER_LENGTH), header,
-		TH_HEADER_LENGTH);	/* put the TH on the packet */
-
-	kfree(header);
-
 	CTCM_PR_DBGDATA("%s: trans_skb len:%04x \n",
 		       __func__, ch->trans_skb->len);
 	CTCM_PR_DBGDATA("%s: up-to-50 bytes of trans_skb "
diff --git a/drivers/s390/net/ctcm_main.c b/drivers/s390/net/ctcm_main.c
index d06809eac16d..9e28c63415ed 100644
--- a/drivers/s390/net/ctcm_main.c
+++ b/drivers/s390/net/ctcm_main.c
@@ -623,25 +623,10 @@ static void ctcmpc_send_sweep_req(struct channel *rch)
 				goto nomem;
 	}
 
-	header = kmalloc(TH_SWEEP_LENGTH, gfp_type());
-
-	if (!header) {
-		dev_kfree_skb_any(sweep_skb);
-		/* rc = -ENOMEM; */
-				goto nomem;
-	}
-
-	header->th.th_seg	= 0x00 ;
+	header = skb_put_zero(sweep_skb, TH_SWEEP_LENGTH);
 	header->th.th_ch_flag	= TH_SWEEP_REQ;  /* 0x0f */
-	header->th.th_blk_flag	= 0x00;
-	header->th.th_is_xid	= 0x00;
-	header->th.th_seq_num	= 0x00;
 	header->sw.th_last_seq	= ch->th_seq_num;
 
-	skb_put_data(sweep_skb, header, TH_SWEEP_LENGTH);
-
-	kfree(header);
-
 	netif_trans_update(dev);
 	skb_queue_tail(&ch->sweep_queue, sweep_skb);
 
@@ -768,25 +753,17 @@ static int ctcmpc_transmit_skb(struct channel *ch, struct sk_buff *skb)
 
 	ch->prof.txlen += skb->len - PDU_HEADER_LENGTH;
 
-	header = kmalloc(TH_HEADER_LENGTH, gfp_type());
-	if (!header)
-		goto nomem_exit;
+	/* put the TH on the packet */
+	header = skb_push(skb, TH_HEADER_LENGTH);
+	memset(header, 0, TH_HEADER_LENGTH);
 
-	header->th_seg = 0x00;
 	header->th_ch_flag = TH_HAS_PDU;  /* Normal data */
-	header->th_blk_flag = 0x00;
-	header->th_is_xid = 0x00;          /* Just data here */
 	ch->th_seq_num++;
 	header->th_seq_num = ch->th_seq_num;
 
 	CTCM_PR_DBGDATA("%s(%s) ToVTAM_th_seq= %08x\n" ,
 		       __func__, dev->name, ch->th_seq_num);
 
-	/* put the TH on the packet */
-	memcpy(skb_push(skb, TH_HEADER_LENGTH), header, TH_HEADER_LENGTH);
-
-	kfree(header);
-
 	CTCM_PR_DBGDATA("%s(%s): skb len: %04x\n - pdu header and data for "
 			"up to 32 bytes sent to vtam:\n",
 				__func__, dev->name, skb->len);
diff --git a/drivers/s390/net/ctcm_mpc.c b/drivers/s390/net/ctcm_mpc.c
index 85a1a4533cbe..293d8870968c 100644
--- a/drivers/s390/net/ctcm_mpc.c
+++ b/drivers/s390/net/ctcm_mpc.c
@@ -655,24 +655,10 @@ static void ctcmpc_send_sweep_resp(struct channel *rch)
 		goto done;
 	}
 
-	header = kmalloc(sizeof(struct th_sweep), gfp_type());
-
-	if (!header) {
-		dev_kfree_skb_any(sweep_skb);
-		goto done;
-	}
-
-	header->th.th_seg	= 0x00 ;
+	header = skb_put_zero(sweep_skb, TH_SWEEP_LENGTH);
 	header->th.th_ch_flag	= TH_SWEEP_RESP;
-	header->th.th_blk_flag	= 0x00;
-	header->th.th_is_xid	= 0x00;
-	header->th.th_seq_num	= 0x00;
 	header->sw.th_last_seq	= ch->th_seq_num;
 
-	skb_put_data(sweep_skb, header, TH_SWEEP_LENGTH);
-
-	kfree(header);
-
 	netif_trans_update(dev);
 	skb_queue_tail(&ch->sweep_queue, sweep_skb);
 
-- 
2.17.1

Re: [PATCH net-next 1/6] s390/ctcm: Avoid temporary allocation of struct th_header and th_sweep.

[Jakub Kicinski]

On Mon, 30 Nov 2020 11:09:45 +0100 Julian Wiedmann wrote:
> From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> 
> The size of struct th_header is 8 byte and the size of struct th_sweep
> is 16 byte. The memory for is allocated, initialized, used and
> deallocated a few lines later.
> 
> It is more efficient to avoid the allocation/free dance and assign the
> values directly to skb's data part instead of using memcpy() for it.
> 
> Avoid an allocation of struct th_sweep/th_header and use the resulting
> skb pointer instead.
> 
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> [jwi: use skb_put_zero(), instead of skb_put() + memset to 0]
> Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>

Stuff like that is usually done when skb data cannot be assumed to be
aligned. I don't see where the skbs are allocated here, so fingers
crossed :)

[PATCH net-next 2/6] s390/ctcm: Avoid temporary allocation of struct qllc.

[Julian Wiedmann]

From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

The size of struct qllc is 2 byte. The memory for is allocated,
initialized, used and deallocated a few lines later.

It is more efficient to avoid the allocation/free dance and assign the
values directly to skb's data part instead of using memcpy() for it.

Avoid an allocation of struct qllc and use the resulting skb pointer
instead.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
[jwi: remove a newline, reflow the commit msg]
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
---
 drivers/s390/net/ctcm_mpc.c | 21 ++++-----------------
 1 file changed, 4 insertions(+), 17 deletions(-)

diff --git a/drivers/s390/net/ctcm_mpc.c b/drivers/s390/net/ctcm_mpc.c
index 293d8870968c..8ae49732d1d2 100644
--- a/drivers/s390/net/ctcm_mpc.c
+++ b/drivers/s390/net/ctcm_mpc.c
@@ -2048,7 +2048,6 @@ static void mpc_action_rcvd_xid7(fsm_instance *fsm, int event, void *arg)
  */
 static int mpc_send_qllc_discontact(struct net_device *dev)
 {
-	__u32	new_len	= 0;
 	struct sk_buff   *skb;
 	struct qllc      *qllcptr;
 	struct ctcm_priv *priv = dev->ml_priv;
@@ -2079,31 +2078,19 @@ static int mpc_send_qllc_discontact(struct net_device *dev)
 	case MPCG_STATE_FLOWC:
 	case MPCG_STATE_READY:
 		grp->send_qllc_disc = 2;
-		new_len = sizeof(struct qllc);
-		qllcptr = kzalloc(new_len, gfp_type() | GFP_DMA);
-		if (qllcptr == NULL) {
-			CTCM_DBF_TEXT_(MPC_ERROR, CTC_DBF_ERROR,
-				"%s(%s): qllcptr allocation error",
-						CTCM_FUNTAIL, dev->name);
-			return -ENOMEM;
-		}
-
-		qllcptr->qllc_address = 0xcc;
-		qllcptr->qllc_commands = 0x03;
-
-		skb = __dev_alloc_skb(new_len, GFP_ATOMIC);
 
+		skb = __dev_alloc_skb(sizeof(struct qllc), GFP_ATOMIC);
 		if (skb == NULL) {
 			CTCM_DBF_TEXT_(MPC_ERROR, CTC_DBF_ERROR,
 				"%s(%s): skb allocation error",
 						CTCM_FUNTAIL, dev->name);
 			priv->stats.rx_dropped++;
-			kfree(qllcptr);
 			return -ENOMEM;
 		}
 
-		skb_put_data(skb, qllcptr, new_len);
-		kfree(qllcptr);
+		qllcptr = skb_put(skb, sizeof(struct qllc));
+		qllcptr->qllc_address = 0xcc;
+		qllcptr->qllc_commands = 0x03;
 
 		if (skb_headroom(skb) < 4) {
 			CTCM_DBF_TEXT_(MPC_ERROR, CTC_DBF_ERROR,
-- 
2.17.1

[PATCH net-next 3/6] s390/ctcm: Avoid temporary allocation of struct pdu.

[Julian Wiedmann]

From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

The size of struct pdu is 8 byte. The memory is allocated, initialized,
used and deallocated a few lines later.

It is more efficient to avoid the allocation/free dance and assign the
values directly to skb's data part instead of using memcpy() for it.

Avoid an allocation of struct pdu and use the resulting skb pointer
instead.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
[jwi: Fix-up the pdu_offset, adjust skb->len for the pushed length.
      Reflow the commit msg.]
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
---
 drivers/s390/net/ctcm_main.c | 33 ++++++++-------------------------
 1 file changed, 8 insertions(+), 25 deletions(-)

diff --git a/drivers/s390/net/ctcm_main.c b/drivers/s390/net/ctcm_main.c
index 9e28c63415ed..92dd3c803d23 100644
--- a/drivers/s390/net/ctcm_main.c
+++ b/drivers/s390/net/ctcm_main.c
@@ -665,24 +665,16 @@ static int ctcmpc_transmit_skb(struct channel *ch, struct sk_buff *skb)
 	if ((fsm_getstate(ch->fsm) != CTC_STATE_TXIDLE) || grp->in_sweep) {
 		spin_lock_irqsave(&ch->collect_lock, saveflags);
 		refcount_inc(&skb->users);
-		p_header = kmalloc(PDU_HEADER_LENGTH, gfp_type());
 
-		if (!p_header) {
-			spin_unlock_irqrestore(&ch->collect_lock, saveflags);
-				goto nomem_exit;
-		}
-
-		p_header->pdu_offset = skb->len;
+		p_header = skb_push(skb, PDU_HEADER_LENGTH);
+		p_header->pdu_offset = skb->len - PDU_HEADER_LENGTH;
 		p_header->pdu_proto = 0x01;
-		p_header->pdu_flag = 0x00;
 		if (be16_to_cpu(skb->protocol) == ETH_P_SNAP) {
-			p_header->pdu_flag |= PDU_FIRST | PDU_CNTL;
+			p_header->pdu_flag = PDU_FIRST | PDU_CNTL;
 		} else {
-			p_header->pdu_flag |= PDU_FIRST;
+			p_header->pdu_flag = PDU_FIRST;
 		}
 		p_header->pdu_seq = 0;
-		memcpy(skb_push(skb, PDU_HEADER_LENGTH), p_header,
-		       PDU_HEADER_LENGTH);
 
 		CTCM_PR_DEBUG("%s(%s): Put on collect_q - skb len: %04x \n"
 				"pdu header and data for up to 32 bytes:\n",
@@ -691,7 +683,6 @@ static int ctcmpc_transmit_skb(struct channel *ch, struct sk_buff *skb)
 
 		skb_queue_tail(&ch->collect_queue, skb);
 		ch->collect_len += skb->len;
-		kfree(p_header);
 
 		spin_unlock_irqrestore(&ch->collect_lock, saveflags);
 			goto done;
@@ -721,23 +712,15 @@ static int ctcmpc_transmit_skb(struct channel *ch, struct sk_buff *skb)
 		}
 	}
 
-	p_header = kmalloc(PDU_HEADER_LENGTH, gfp_type());
-
-	if (!p_header)
-		goto nomem_exit;
-
-	p_header->pdu_offset = skb->len;
+	p_header = skb_push(skb, PDU_HEADER_LENGTH);
+	p_header->pdu_offset = skb->len - PDU_HEADER_LENGTH;
 	p_header->pdu_proto = 0x01;
-	p_header->pdu_flag = 0x00;
 	p_header->pdu_seq = 0;
 	if (be16_to_cpu(skb->protocol) == ETH_P_SNAP) {
-		p_header->pdu_flag |= PDU_FIRST | PDU_CNTL;
+		p_header->pdu_flag = PDU_FIRST | PDU_CNTL;
 	} else {
-		p_header->pdu_flag |= PDU_FIRST;
+		p_header->pdu_flag = PDU_FIRST;
 	}
-	memcpy(skb_push(skb, PDU_HEADER_LENGTH), p_header, PDU_HEADER_LENGTH);
-
-	kfree(p_header);
 
 	if (ch->collect_len > 0) {
 		spin_lock_irqsave(&ch->collect_lock, saveflags);
-- 
2.17.1

[PATCH net-next 4/6] s390/ctcm: Use explicit allocation mask in ctcmpc_unpack_skb().

[Julian Wiedmann]

From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

gfp_type() uses in_interrupt() to figure out the correct GFP mask.

The usage of in_interrupt() in drivers is phased out and Linus clearly
requested that code which changes behaviour depending on context should
either be separated or the context be conveyed in an argument passed by the
caller, which usually knows the context.

The call chain of ctcmpc_unpack_skb():
ctcmpc_bh()
 -> ctcmpc_unpack_skb()

ctcmpc_bh() is a tasklet handler so GFP_ATOMIC is needed.

Use GFP_ATOMIC as allocation type in ctcmpc_unpack_skb().

Reviewed-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
---
 drivers/s390/net/ctcm_mpc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/s390/net/ctcm_mpc.c b/drivers/s390/net/ctcm_mpc.c
index 8ae49732d1d2..19ee91acb89d 100644
--- a/drivers/s390/net/ctcm_mpc.c
+++ b/drivers/s390/net/ctcm_mpc.c
@@ -1163,7 +1163,7 @@ static void ctcmpc_unpack_skb(struct channel *ch, struct sk_buff *pskb)
 			skb_pull(pskb, new_len); /* point to next PDU */
 		}
 	} else {
-		mpcginfo = kmalloc(sizeof(struct mpcg_info), gfp_type());
+		mpcginfo = kmalloc(sizeof(struct mpcg_info), GFP_ATOMIC);
 		if (mpcginfo == NULL)
 					goto done;
 
-- 
2.17.1

[PATCH net-next 5/6] s390/ctcm: Use GFP_KERNEL in add_channel().

[Julian Wiedmann]

From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

gfp_type() uses in_interrupt() to figure out the correct GFP mask.

The usage of in_interrupt() in drivers is phased out and Linus clearly
requested that code which changes behaviour depending on context should
either be separated or the context be conveyed in an argument passed by the
caller, which usually knows the context.

The memory allocation of `ch' a few lines above is using GFP_KERNEL,
also an allocation a few lines later is using GFP_KERNEL.

Use GFP_KERNEL for the memory allocation.

Reviewed-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
---
 drivers/s390/net/ctcm_main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/s390/net/ctcm_main.c b/drivers/s390/net/ctcm_main.c
index 92dd3c803d23..c446883de5c8 100644
--- a/drivers/s390/net/ctcm_main.c
+++ b/drivers/s390/net/ctcm_main.c
@@ -1321,7 +1321,7 @@ static int add_channel(struct ccw_device *cdev, enum ctcm_channel_types type,
 
 	ch->protocol = priv->protocol;
 	if (IS_MPC(priv)) {
-		ch->discontact_th = kzalloc(TH_HEADER_LENGTH, gfp_type());
+		ch->discontact_th = kzalloc(TH_HEADER_LENGTH, GFP_KERNEL);
 		if (ch->discontact_th == NULL)
 					goto nomem_return;
 
-- 
2.17.1

[PATCH net-next 6/6] s390/ctcm: Use GFP_ATOMIC in ctcmpc_tx().

[Julian Wiedmann]

From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

gfp_type() uses in_interrupt() to figure out the correct GFP mask.

The usage of in_interrupt() in drivers is phased out and Linus clearly
requested that code which changes behaviour depending on context should
either be separated or the context be conveyed in an argument passed by the
caller, which usually knows the context.

ctcmpc_tx() is used as net_device_ops::ndo_start_xmit. This callback is
invoked with disabled bottom halves.

Use GFP_ATOMIC for memory allocation in ctcmpc_tx().
Remove gfp_type() since the last user is gone.

Reviewed-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
---
 drivers/s390/net/ctcm_main.c | 2 +-
 drivers/s390/net/ctcm_main.h | 5 -----
 2 files changed, 1 insertion(+), 6 deletions(-)

diff --git a/drivers/s390/net/ctcm_main.c b/drivers/s390/net/ctcm_main.c
index c446883de5c8..fd705429708e 100644
--- a/drivers/s390/net/ctcm_main.c
+++ b/drivers/s390/net/ctcm_main.c
@@ -903,7 +903,7 @@ static int ctcmpc_tx(struct sk_buff *skb, struct net_device *dev)
 		CTCM_D3_DUMP((char *)skb->data, min_t(int, 32, skb->len));
 
 		len =  skb->len + TH_HEADER_LENGTH + PDU_HEADER_LENGTH;
-		newskb = __dev_alloc_skb(len, gfp_type() | GFP_DMA);
+		newskb = __dev_alloc_skb(len, GFP_ATOMIC | GFP_DMA);
 
 		if (!newskb) {
 			CTCM_DBF_TEXT_(MPC_TRACE, CTC_DBF_ERROR,
diff --git a/drivers/s390/net/ctcm_main.h b/drivers/s390/net/ctcm_main.h
index 16bdf23ee02b..90bd7b3f80c3 100644
--- a/drivers/s390/net/ctcm_main.h
+++ b/drivers/s390/net/ctcm_main.h
@@ -298,11 +298,6 @@ struct mpc_group *ctcmpc_init_mpc_group(struct ctcm_priv *priv);
 /* test if struct ctcm_priv of struct net_device has MPC protocol setting */
 #define IS_MPCDEV(dev) IS_MPC((struct ctcm_priv *)dev->ml_priv)
 
-static inline gfp_t gfp_type(void)
-{
-	return in_interrupt() ? GFP_ATOMIC : GFP_KERNEL;
-}
-
 /*
  * Definition of our link level header.
  */
-- 
2.17.1

Re: [PATCH net-next 0/6] s390/ctcm: updates 2020-11-30

[Jakub Kicinski]

On Mon, 30 Nov 2020 11:09:44 +0100 Julian Wiedmann wrote:
> Some rare ctcm updates by Sebastian, who cleans up all places where
> in_interrupt() was used to determine the correct GFP_* mask for
> allocations.
> In the first three patches we can get rid of those allocations entirely,
> as they just end up being copied into the skb.

Applied, thanks!