drivers/scsi/libfc/fc_exch.c

Source file repositories/reference/linux-study-clean/drivers/scsi/libfc/fc_exch.c

File Facts

System
Linux kernel
Corpus path
drivers/scsi/libfc/fc_exch.c
Extension
.c
Size
72625 bytes
Lines
2714
Domain
Driver Families
Bucket
drivers/scsi
Inferred role
Driver Families: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

struct fc_exch_pool {
	spinlock_t	 lock;
	struct list_head ex_list;
	u16		 next_index;
	u16		 total_exches;

	u16		 left;
	u16		 right;
} ____cacheline_aligned_in_smp;

/**
 * struct fc_exch_mgr - The Exchange Manager (EM).
 * @class:	    Default class for new sequences
 * @kref:	    Reference counter
 * @min_xid:	    Minimum exchange ID
 * @max_xid:	    Maximum exchange ID
 * @ep_pool:	    Reserved exchange pointers
 * @pool_max_index: Max exch array index in exch pool
 * @pool:	    Per cpu exch pool
 * @lport:	    Local exchange port
 * @stats:	    Statistics structure
 *
 * This structure is the center for creating exchanges and sequences.
 * It manages the allocation of exchange IDs.
 */
struct fc_exch_mgr {
	struct fc_exch_pool __percpu *pool;
	mempool_t	*ep_pool;
	struct fc_lport	*lport;
	enum fc_class	class;
	struct kref	kref;
	u16		min_xid;
	u16		max_xid;
	u16		pool_max_index;

	struct {
		atomic_t no_free_exch;
		atomic_t no_free_exch_xid;
		atomic_t xid_not_found;
		atomic_t xid_busy;
		atomic_t seq_not_found;
		atomic_t non_bls_resp;
	} stats;
};

/**
 * struct fc_exch_mgr_anchor - primary structure for list of EMs
 * @ema_list: Exchange Manager Anchor list
 * @mp:	      Exchange Manager associated with this anchor
 * @match:    Routine to determine if this anchor's EM should be used
 *
 * When walking the list of anchors the match routine will be called
 * for each anchor to determine if that EM should be used. The last
 * anchor in the list will always match to handle any exchanges not
 * handled by other EMs. The non-default EMs would be added to the
 * anchor list by HW that provides offloads.
 */
struct fc_exch_mgr_anchor {
	struct list_head ema_list;
	struct fc_exch_mgr *mp;
	bool (*match)(struct fc_frame *);
};

static void fc_exch_rrq(struct fc_exch *);
static void fc_seq_ls_acc(struct fc_frame *);
static void fc_seq_ls_rjt(struct fc_frame *, enum fc_els_rjt_reason,
			  enum fc_els_rjt_explan);
static void fc_exch_els_rec(struct fc_frame *);
static void fc_exch_els_rrq(struct fc_frame *);

/*
 * Internal implementation notes.
 *
 * The exchange manager is one by default in libfc but LLD may choose
 * to have one per CPU. The sequence manager is one per exchange manager
 * and currently never separated.
 *
 * Section 9.8 in FC-FS-2 specifies:  "The SEQ_ID is a one-byte field
 * assigned by the Sequence Initiator that shall be unique for a specific
 * D_ID and S_ID pair while the Sequence is open."   Note that it isn't
 * qualified by exchange ID, which one might think it would be.
 * In practice this limits the number of open sequences and exchanges to 256
 * per session.	 For most targets we could treat this limit as per exchange.
 *
 * The exchange and its sequence are freed when the last sequence is received.
 * It's possible for the remote port to leave an exchange open without
 * sending any sequences.
 *
 * Notes on reference counts:
 *

Annotation

Implementation Notes