ata: libata-core: Remove support for decreasing the number of ports

Commit f318719 ("libata: separate out ata_host_alloc() and
ata_host_register()") added ata_host_alloc(), where the API allowed
a LLD to overallocate the number of ports supplied to ata_host_alloc(),
as long as the LLD decreased host->n_ports before calling
ata_host_register().

However, this functionally has never ever been used by a single LLD.

Because of the current API design, the assignment of ap->print_id is
deferred until registration time, which is bad, because that means that
the ata_port_*() print functions cannot be used by a LLD until after
registration time, which means that a LLD is forced to use a print
function that is non-port specific, even for a port specific error.

Remove the support for decreasing the number of ports, such that it will
be possible to assign ap->print_id earlier.

Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20240703184418.723066-14-cassel@kernel.org
Signed-off-by: Niklas Cassel <cassel@kernel.org>

Author: floatious

drivers/ata/libata-core.c

@@ -5555,32 +5555,27 @@ EXPORT_SYMBOL_GPL(ata_host_put);
 /**
  *	ata_host_alloc - allocate and init basic ATA host resources
  *	@dev: generic device this host is associated with
- *	@max_ports: maximum number of ATA ports associated with this host
+ *	@n_ports: the number of ATA ports associated with this host
  *
  *	Allocate and initialize basic ATA host resources.  LLD calls
  *	this function to allocate a host, initializes it fully and
  *	attaches it using ata_host_register().
  *
- *	@max_ports ports are allocated and host->n_ports is
- *	initialized to @max_ports.  The caller is allowed to decrease
- *	host->n_ports before calling ata_host_register().  The unused
- *	ports will be automatically freed on registration.
- *
  *	RETURNS:
  *	Allocate ATA host on success, NULL on failure.
  *
  *	LOCKING:
  *	Inherited from calling layer (may sleep).
  */
-struct ata_host *ata_host_alloc(struct device *dev, int max_ports)
+struct ata_host *ata_host_alloc(struct device *dev, int n_ports)
 {
 	struct ata_host *host;
 	size_t sz;
 	int i;
 	void *dr;
 
 	/* alloc a container for our list of ATA ports (buses) */
-	sz = sizeof(struct ata_host) + (max_ports + 1) * sizeof(void *);
+	sz = sizeof(struct ata_host) + n_ports * sizeof(void *);
 	host = kzalloc(sz, GFP_KERNEL);
 	if (!host)
 		return NULL;
@@ -5600,11 +5595,11 @@ struct ata_host *ata_host_alloc(struct device *dev, int max_ports)
 	spin_lock_init(&host->lock);
 	mutex_init(&host->eh_mutex);
 	host->dev = dev;
-	host->n_ports = max_ports;
+	host->n_ports = n_ports;
 	kref_init(&host->kref);
 
 	/* allocate ports bound to this host */
-	for (i = 0; i < max_ports; i++) {
+	for (i = 0; i < n_ports; i++) {
 		struct ata_port *ap;
 
 		ap = ata_port_alloc(host);
@@ -5913,13 +5908,6 @@ int ata_host_register(struct ata_host *host, const struct scsi_host_template *sh
 		return -EINVAL;
 	}
 
-	/* Blow away unused ports.  This happens when LLD can't
-	 * determine the exact number of ports to allocate at
-	 * allocation time.
-	 */
-	for (i = host->n_ports; host->ports[i]; i++)
-		ata_port_free(host->ports[i]);
-
 	/* give ports names and add SCSI hosts */
 	for (i = 0; i < host->n_ports; i++) {
 		host->ports[i]->print_id = atomic_inc_return(&ata_print_id);

include/linux/libata.h

@@ -1069,7 +1069,7 @@ extern int sata_std_hardreset(struct ata_link *link, unsigned int *class,
 			      unsigned long deadline);
 extern void ata_std_postreset(struct ata_link *link, unsigned int *classes);
 
-extern struct ata_host *ata_host_alloc(struct device *dev, int max_ports);
+extern struct ata_host *ata_host_alloc(struct device *dev, int n_ports);
 extern struct ata_host *ata_host_alloc_pinfo(struct device *dev,
 			const struct ata_port_info * const * ppi, int n_ports);
 extern void ata_host_get(struct ata_host *host);