Date:	Mon, 21 Mar 2011 23:04:16 -0500
From:	Mike Christie <michaelc@...wisc.edu>
To:	"Nicholas A. Bellinger" <nab@...ux-iscsi.org>
CC:	linux-scsi <linux-scsi@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	James Bottomley <James.Bottomley@...senPartnership.com>,
	Christoph Hellwig <hch@....de>, Hannes Reinecke <hare@...e.de>,
	FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>,
	Boaz Harrosh <bharrosh@...asas.com>,
	Stephen Rothwell <sfr@...b.auug.org.au>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Douglas Gilbert <dgilbert@...erlog.com>,
	Jesper Juhl <jj@...osbits.net>
Subject: Re: [RFC-v4 11/12] iscsi-target: Add misc utility and debug logic

On 03/20/2011 04:31 AM, Nicholas A. Bellinger wrote

> +
> +/*
> + *	Called with cmd->r2t_lock held.
> + */
> +void iscsit_free_r2t(struct iscsi_r2t *r2t, struct iscsi_cmd *cmd)
> +{
> +	list_del(&r2t->r2t_list);
> +	kmem_cache_free(lio_r2t_cache, r2t);
> +}
> +
> +void iscsit_free_r2ts_from_list(struct iscsi_cmd *cmd)
> +{
> +	struct iscsi_r2t *r2t, *r2t_tmp;
> +
> +	spin_lock_bh(&cmd->r2t_lock);
> +	list_for_each_entry_safe(r2t, r2t_tmp,&cmd->cmd_r2t_list, r2t_list) {
> +		list_del(&r2t->r2t_list);
> +		kmem_cache_free(lio_r2t_cache, r2t);

I think that is iscsit_free_r2t()

> +	}
> +	spin_unlock_bh(&cmd->r2t_lock);
> +}
> +
> +/*
> + *	May be called from interrupt context.


How does this get called from interrupt context? Is it a real interrupt 
or a soft irq? I could not find the code path.





> +
> +struct iscsi_r2t *iscsit_get_holder_for_r2tsn(
> +	struct iscsi_cmd *cmd,
> +	u32 r2t_sn)
> +{
> +	struct iscsi_r2t *r2t;
> +
> +	spin_lock_bh(&cmd->r2t_lock);
> +	list_for_each_entry(r2t,&cmd->cmd_r2t_list, r2t_list) {
> +		if (r2t->r2t_sn == r2t_sn)
> +			break;
> +	}
> +	spin_unlock_bh(&cmd->r2t_lock);
> +
> +	return (r2t) ? r2t : NULL;

Don't need "( ")".


> +}
> +
> +#define SERIAL_BITS	31
> +#define MAX_BOUND	(u32)2147483647UL
> +
> +static inline int serial_lt(u32 x, u32 y)
> +{
> +	return (x != y)&&  (((x<  y)&&  ((y - x)<  MAX_BOUND)) ||
> +		((x>  y)&&  ((x - y)>  MAX_BOUND)));
> +}
> +
> +static inline int serial_lte(u32 x, u32 y)
> +{
> +	return (x == y) ? 1 : serial_lt(x, y);
> +}
> +
> +static inline int serial_gt(u32 x, u32 y)
> +{
> +	return (x != y)&&  (((x<  y)&&  ((y - x)>  MAX_BOUND)) ||
> +		((x>  y)&&  ((x - y)<  MAX_BOUND)));
> +}
> +
> +static inline int serial_gte(u32 x, u32 y)
> +{
> +	return (x == y) ? 1 : serial_gt(x, y);
> +}


You should merged these with libiscsi.c's iscsi_sna_* and put in 
iscsi_proto.h.

I think this is not iscsi specific is it? It seems like it could go 
someone more generic.



> +void iscsit_release_cmd_direct(struct iscsi_cmd *cmd)
> +{
> +	iscsit_free_r2ts_from_list(cmd);
> +	iscsit_free_all_datain_reqs(cmd);
> +
> +	kfree(cmd->buf_ptr);
> +	kfree(cmd->pdu_list);
> +	kfree(cmd->seq_list);
> +	kfree(cmd->tmr_req);
> +	kfree(cmd->iov_data);
> +
> +	kmem_cache_free(lio_cmd_cache, cmd);
> +}
> +
> +void __iscsit_release_cmd_to_pool(struct iscsi_cmd *cmd, struct iscsi_session *sess)
> +{
> +	struct iscsi_conn *conn = cmd->conn;
> +
> +	iscsit_free_r2ts_from_list(cmd);
> +	iscsit_free_all_datain_reqs(cmd);
> +
> +	kfree(cmd->buf_ptr);
> +	kfree(cmd->pdu_list);
> +	kfree(cmd->seq_list);
> +	kfree(cmd->tmr_req);
> +	kfree(cmd->iov_data);
> +
> +	if (conn) {
> +		iscsit_remove_cmd_from_immediate_queue(cmd, conn);
> +		iscsit_remove_cmd_from_response_queue(cmd, conn);
> +	}
> +
> +	kmem_cache_free(lio_cmd_cache, cmd);
> +}

sess is not used and I could not figure the _to_pool part of the name.

This is not some sort of mistake, right? iscsit_release_cmd_direct and 
__iscsit_release_cmd_to_pool look alike except for the conn check 
related code. Did you mean to merge those functions?



> +
> +void iscsit_release_cmd_to_pool(struct iscsi_cmd *cmd)
> +{
> +	if (!cmd->conn&&  !cmd->sess) {
> +		iscsit_release_cmd_direct(cmd);
> +	} else {
> +		__iscsit_release_cmd_to_pool(cmd, (cmd->conn) ?
> +			cmd->conn->sess : cmd->sess);
> +	}
> +}
> +
> +/*
> + *	Routine to pack an ordinary (LINUX) LUN 32-bit number
> + *		into an 8-byte LUN structure
> + *	(see SAM-2, Section 4.12.3 page 39)
> + *	Thanks to UNH for help with this :-).
> + */
> +inline u64 iscsit_pack_lun(unsigned int lun)
> +{
> +	u64	result;
> +
> +	result = ((lun&  0xff)<<  8);	/* LSB of lun into byte 1 big-endian */
> +
> +	if (0) {
> +		/* use flat space addressing method, SAM-2 Section 4.12.4
> +			-	high-order 2 bits of byte 0 are 01
> +			-	low-order 6 bits of byte 0 are MSB of the lun
> +			-	all 8 bits of byte 1 are LSB of the lun
> +			-	all other bytes (2 thru 7) are 0
> +		 */
> +		result |= 0x40 | ((lun>>  8)&  0x3f);
> +	}
> +	/* else use peripheral device addressing method, Sam-2 Section 4.12.5
> +			-	high-order 2 bits of byte 0 are 00
> +			-	low-order 6 bits of byte 0 are all 0
> +			-	all 8 bits of byte 1 are the lun
> +			-	all other bytes (2 thru 7) are 0
> +	*/
> +
> +	return cpu_to_le64(result);
> +}

Is this int_to_scsilun?


> +
> +/*
> + *	Routine to pack an 8-byte LUN structure into a ordinary (LINUX) 32-bit
> + *	LUN number (see SAM-2, Section 4.12.3 page 39)
> + *	Thanks to UNH for help with this :-).
> + */
> +inline u32 iscsit_unpack_lun(unsigned char *lun_ptr)
> +{
> +	u32	result, temp;
> +
> +	result = *(lun_ptr+1);  /* LSB of lun from byte 1 big-endian */
> +
> +	switch (temp = ((*lun_ptr)>>6)) { /* high 2 bits of byte 0 big-endian */
> +	case 0: /* peripheral device addressing method, Sam-2 Section 4.12.5
> +		-	high-order 2 bits of byte 0 are 00
> +		-	low-order 6 bits of byte 0 are all 0
> +		-	all 8 bits of byte 1 are the lun
> +		-	all other bytes (2 thru 7) are 0
> +		 */
> +		if (*lun_ptr != 0) {
> +			printk(KERN_ERR "Illegal Byte 0 in LUN peripheral"
> +				" device addressing method %u, expected 0\n",
> +				*lun_ptr);
> +		}
> +		break;
> +	case 1: /* flat space addressing method, SAM-2 Section 4.12.4
> +		-	high-order 2 bits of byte 0 are 01
> +		-	low-order 6 bits of byte 0 are MSB of the lun
> +		-	all 8 bits of byte 1 are LSB of the lun
> +		-	all other bytes (2 thru 7) are 0
> +		 */
> +		result += ((*lun_ptr)&  0x3f)<<  8;
> +		break;
> +	default: /* (extended) logical unit addressing */
> +		printk(KERN_ERR "Unimplemented LUN addressing method %u, "
> +			"PDA method used instead\n", temp);
> +		break;
> +	}
> +
> +	return result;
> +}


scsilun_to_int?





> +
> +int iscsit_check_session_usage_count(struct iscsi_session *sess)
> +{
> +	spin_lock_bh(&sess->session_usage_lock);
> +	if (atomic_read(&sess->session_usage_count)) {
> +		atomic_set(&sess->session_waiting_on_uc, 1);
> +		spin_unlock_bh(&sess->session_usage_lock);
> +		if (in_interrupt())
> +			return 2;
> +
> +		wait_for_completion(&sess->session_waiting_on_uc_comp);
> +		return 1;
> +	}
> +	spin_unlock_bh(&sess->session_usage_lock);
> +
> +	return 0;
> +}
> +
> +void iscsit_dec_session_usage_count(struct iscsi_session *sess)
> +{
> +	spin_lock_bh(&sess->session_usage_lock);
> +	atomic_dec(&sess->session_usage_count);
> +
> +	if (!atomic_read(&sess->session_usage_count)&&
> +	     atomic_read(&sess->session_waiting_on_uc))
> +		complete(&sess->session_waiting_on_uc_comp);
> +
> +	spin_unlock_bh(&sess->session_usage_lock);
> +}
> +
> +void iscsit_inc_session_usage_count(struct iscsi_session *sess)
> +{
> +	spin_lock_bh(&sess->session_usage_lock);
> +	atomic_inc(&sess->session_usage_count);
> +	spin_unlock_bh(&sess->session_usage_lock);
> +}



It seems strange for the session_usage_count and waiting_on_uc to be 
atomic and accessed under the spin lock. I think you normally do one or 
the other.



> +
> +unsigned char *iscsit_ntoa(u32 ip)
> +{
> +	static unsigned char buf[18];
> +
> +	memset(buf, 0, 18);
> +	sprintf(buf, "%u.%u.%u.%u", ((ip>>  24)&  0xff), ((ip>>  16)&  0xff),
> +			((ip>>  8)&  0xff), (ip&  0xff));
> +
> +	return buf;
> +}

Nothing is using this. Remove.


> +
> +void iscsit_ntoa2(unsigned char *buf, u32 ip)
> +{
> +	memset(buf, 0, 18);
> +	sprintf(buf, "%u.%u.%u.%u", ((ip>>  24)&  0xff), ((ip>>  16)&  0xff),
> +			((ip>>  8)&  0xff), (ip&  0xff));
> +}

I think we have a function like this already.


If not, I think this should be:

sprintf(buf, "%pI4",

What s up with ipv6 btw? That uses %pI6.


> +
> +#define NS_INT16SZ	 2
> +#define NS_INADDRSZ	 4
> +#define NS_IN6ADDRSZ	16
> +
> +/* const char *
> + * inet_ntop4(src, dst, size)
> + *	format an IPv4 address
> + * return:
> + *	`dst' (as a const)
> + * notes:
> + *	(1) uses no statics
> + *	(2) takes a unsigned char* not an in_addr as input
> + * author:
> + *	Paul Vixie, 1996.
> + */
> +static const char *iscsit_ntop4(


Only used by iscsit_ntop6


> +/* const char *
> + * isc_inet_ntop6(src, dst, size)
> + * convert IPv6 binary address into presentation (printable) format
> + * author:
> + *	Paul Vixie, 1996.
> + */
> +const char *iscsit_ntop6(const unsigned char *src, char *dst, size_t size)
> +{


Not used.


> +
> +/* int
> + * inet_pton4(src, dst)
> + *	like inet_aton() but without all the hexadecimal and shorthand.
> + * return:
> + *	1 if `src' is a valid dotted quad, else 0.
> + * notice:
> + *	does not touch `dst' unless it's returning 1.
> + * author:
> + *	Paul Vixie, 1996.
> + */
> +static int iscsit_pton4(const char *src, unsigned char *dst)
> +{



Only used by inet_pton6

> +
> +/* int
> + * inet_pton6(src, dst)
> + *	convert presentation level address to network order binary form.
> + * return:
> + *	1 if `src' is a valid [RFC1884 2.2] address, else 0.
> + * notice:
> + *	(1) does not touch `dst' unless it's returning 1.
> + *	(2) :: in a full address is silently ignored.
> + * credit:
> + *	inspired by Mark Andrews.
> + * author:
> + *	Paul Vixie, 1996.
> + */
> +int iscsit_pton6(const char *src, unsigned char *dst)
> +{
> +	static const char xdigits_l[] = "0123456789abcdef",



Not used.

I think if you needed these functions then they should go into some 
network code. There were not specific to a iscsi target were they.



> +
> +	return NULL;
> +}
> +
> +void iscsit_check_conn_usage_count(struct iscsi_conn *conn)
> +{
> +	spin_lock_bh(&conn->conn_usage_lock);
> +	if (atomic_read(&conn->conn_usage_count)) {
> +		atomic_set(&conn->conn_waiting_on_uc, 1);
> +		spin_unlock_bh(&conn->conn_usage_lock);
> +
> +		wait_for_completion(&conn->conn_waiting_on_uc_comp);
> +		return;
> +	}
> +	spin_unlock_bh(&conn->conn_usage_lock);
> +}
> +
> +void iscsit_dec_conn_usage_count(struct iscsi_conn *conn)
> +{
> +	spin_lock_bh(&conn->conn_usage_lock);
> +	atomic_dec(&conn->conn_usage_count);
> +
> +	if (!atomic_read(&conn->conn_usage_count)&&
> +	     atomic_read(&conn->conn_waiting_on_uc))
> +		complete(&conn->conn_waiting_on_uc_comp);
> +
> +	spin_unlock_bh(&conn->conn_usage_lock);
> +}
> +
> +void iscsit_inc_conn_usage_count(struct iscsi_conn *conn)
> +{
> +	spin_lock_bh(&conn->conn_usage_lock);
> +	atomic_inc(&conn->conn_usage_count);
> +	spin_unlock_bh(&conn->conn_usage_lock);
> +}

Something about atomics and always being accessed under a lock. I think 
this happens in other places too.

Could this also be done with krefs?



> +
> +int iscsit_check_for_active_network_device(struct iscsi_conn *conn)
> +{
> +	struct net_device *net_dev;
> +
> +	if (!conn->net_if) {
> +		printk(KERN_ERR "struct iscsi_conn->net_if is NULL for CID:"
> +			" %hu\n", conn->cid);
> +		return 0;
> +	}
> +	net_dev = conn->net_if;
> +
> +	return netif_carrier_ok(net_dev);
> +}
> +
> +static void iscsit_handle_netif_timeout(unsigned long data)
> +{
> +	struct iscsi_conn *conn = (struct iscsi_conn *) data;
> +
> +	iscsit_inc_conn_usage_count(conn);
> +
> +	spin_lock_bh(&conn->netif_lock);
> +	if (conn->netif_timer_flags&  ISCSI_TF_STOP) {
> +		spin_unlock_bh(&conn->netif_lock);
> +		iscsit_dec_conn_usage_count(conn);
> +		return;
> +	}
> +	conn->netif_timer_flags&= ~ISCSI_TF_RUNNING;
> +
> +	if (iscsit_check_for_active_network_device((void *)conn)) {
> +		iscsit_start_netif_timer(conn);
> +		spin_unlock_bh(&conn->netif_lock);
> +		iscsit_dec_conn_usage_count(conn);
> +		return;
> +	}
> +
> +	printk(KERN_ERR "Detected PHY loss on Network Interface: %s for iSCSI"
> +		" CID: %hu on SID: %u\n", conn->net_dev, conn->cid,
> +			conn->sess->sid);
> +
> +	spin_unlock_bh(&conn->netif_lock);
> +
> +	iscsit_cause_connection_reinstatement(conn, 0);
> +	iscsit_dec_conn_usage_count(conn);
> +}


I think instead of polling the device you can use 
register_netdevice_notifier. See fcoe.c for an example.



> +
> +static inline int iscsit_do_rx_data(
> +	struct iscsi_conn *conn,
> +	struct iscsi_data_count *count)
> +{



> +
> +	while (total_rx<  data) {
> +		oldfs = get_fs();
> +		set_fs(get_ds());
> +
> +		conn->sock->sk->sk_allocation = GFP_ATOMIC;


I do not think you need GFP_ATOMIC. If you cannot sleep then I think you 
are in trouble below, because you pass in MSG_WAITALL.

I think since this is the target side you can use GFP_KERNEL. Target 
mode should not have the same allocation swinging around on you 
dependency problem like a initiator does, does it?

If it does at least use GFP_NOIO (I think iscsi_tcp.c should be using 
GFP_NOIO and not GFP_ATOMIC).

And I think we are supposed to be using kernel_recvmsg. It does the 
get/set_ds stuff for you.


> +		rx_loop = sock_recvmsg(conn->sock,&msg,
> +				(data - total_rx), MSG_WAITALL);
> +




> +static inline int iscsit_do_tx_data(
> +	struct iscsi_conn *conn,
> +	struct iscsi_data_count *count)
> +{



> +
> +	while (total_tx<  data) {
> +		oldfs = get_fs();
> +		set_fs(get_ds());
> +
> +		conn->sock->sk->sk_allocation = GFP_ATOMIC;

Same comment as the recv side. I think you can also move this and set it 
in one place.

And I think we are supposed to be using kernel_sendmsg. That will also 
do the get/set_fs stuff for you.


> +		tx_loop = sock_sendmsg(conn->sock,&msg, (data - total_tx));
> +
> +		set_fs(oldfs);
> +







> +extern int iscsit_build_sendtargets_response(struct iscsi_cmd *cmd)
> +{
> +	char *ip, *payload = NULL;
> +	struct iscsi_conn *conn = cmd->conn;
> +	struct iscsi_portal_group *tpg;
> +	struct iscsi_tiqn *tiqn;
> +	struct iscsi_tpg_np *tpg_np;
> +	int buffer_len, end_of_buf = 0, len = 0, payload_len = 0;
> +	unsigned char buf[256];
> +	unsigned char buf_ipv4[IPV4_BUF_SIZE];
> +
> +	buffer_len = (conn->conn_ops->MaxRecvDataSegmentLength>  32768) ?
> +			32768 : conn->conn_ops->MaxRecvDataSegmentLength;
> +
> +	payload = kzalloc(buffer_len, GFP_KERNEL);
> +	if (!payload) {
> +		printk(KERN_ERR "Unable to allocate memory for sendtargets"
> +			" response.\n");
> +		return -1;
> +	}
> +
> +	spin_lock(&tiqn_lock);
> +	list_for_each_entry(tiqn,&g_tiqn_list, tiqn_list) {
> +		memset(buf, 0, 256);
> +
> +		len = sprintf(buf, "TargetName=%s", tiqn->tiqn);
> +		len += 1;
> +
> +		if ((len + payload_len)>  buffer_len) {
> +			spin_unlock(&tiqn->tiqn_tpg_lock);
> +			end_of_buf = 1;
> +			goto eob;
> +		}
> +		memcpy((void *)payload + payload_len, buf, len);
> +		payload_len += len;
> +
> +		spin_lock(&tiqn->tiqn_tpg_lock);
> +		list_for_each_entry(tpg,&tiqn->tiqn_tpg_list, tpg_list) {
> +
> +			spin_lock(&tpg->tpg_state_lock);
> +			if ((tpg->tpg_state == TPG_STATE_FREE) ||
> +			    (tpg->tpg_state == TPG_STATE_INACTIVE)) {
> +				spin_unlock(&tpg->tpg_state_lock);
> +				continue;
> +			}
> +			spin_unlock(&tpg->tpg_state_lock);
> +
> +			spin_lock(&tpg->tpg_np_lock);
> +			list_for_each_entry(tpg_np,&tpg->tpg_gnp_list,
> +					tpg_np_list) {
> +				memset(buf, 0, 256);
> +
> +				if (tpg_np->tpg_np->np_sockaddr.ss_family == AF_INET6) {
> +					ip =&tpg_np->tpg_np->np_ipv6[0];


Is ip supposed to be a string with the ip address in it? If so is that 
right? Is np_ipv6 a string with the ip address in human readable format, 
but below np_ipv4 is the integer representation then you convert it.


> +				} else {
> +					memset(buf_ipv4, 0, IPV4_BUF_SIZE);
> +					iscsit_ntoa2(buf_ipv4,
> +						tpg_np->tpg_np->np_ipv4);
> +					ip =&buf_ipv4[0];
> +				}
> +
> +				len = sprintf(buf, "TargetAddress="
> +					"%s%s%s:%hu,%hu",
> +					(tpg_np->tpg_np->np_sockaddr.ss_family == AF_INET6) ?
> +					"[" : "", ip,
> +					(tpg_np->tpg_np->np_sockaddr.ss_family == AF_INET6) ?
> +					"]" : "", tpg_np->tpg_np->np_port,
> +					tpg->tpgt);
> +				len += 1;
> +
> +				if ((len + payload_len)>  buffer_len) {
> +					spin_unlock(&tpg->tpg_np_lock);
> +					spin_unlock(&tiqn->tiqn_tpg_lock);
> +					end_of_buf = 1;
> +					goto eob;
> +				}
> +
> +				memcpy((void *)payload + payload_len, buf, len);
> +				payload_len += len;
> +			}
> +			spin_unlock(&tpg->tpg_np_lock);
> +		}
> +		spin_unlock(&tiqn->tiqn_tpg_lock);
> +eob:
> +		if (end_of_buf)
> +			break;
> +	}
> +	spin_unlock(&tiqn_lock);
> +
> +	cmd->buf_ptr = payload;
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