Merge branch 'for-3.16-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/libata (ea9339e5) · Commits · 戴 / test

Pull libata regression fix from Tejun Heo: "The last libata/for-3.16-fixes pull contained a regression introduced by ("libata: support the ata host which implements a queue depth less than 32") which in turn was a fix for a regression introduced earlier while changing queue tag order to accomodate hard drives which perform poorly if tags are not allocated in circular order (ugh...). The regression happens only for SAS controllers making use of libata to serve ATA devices. They don't fill an ata_host field which is used by the new tag allocation function leading to NULL dereference. This patch adds a new intermediate field ata_host->n_tags which is initialized for both SAS and !SAS cases to fix the issue" * 'for-3.16-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/libata: libata: introduce ata_host->n_tags to avoid oops on SAS controllers

drivers/ata/libata-core.c

+4 −12

Original line number	Diff line number	Diff line
		@@ -4798,9 +4798,8 @@ void swap_buf_le16(u16 *buf, unsigned int buf_words)
		static struct ata_queued_cmd ata_qc_new(struct ata_port ap)
		{
		struct ata_queued_cmd *qc = NULL;
		unsigned int i, tag, max_queue;

		max_queue = ap->scsi_host->can_queue;
		unsigned int max_queue = ap->host->n_tags;
		unsigned int i, tag;

		/* no command while frozen */
		if (unlikely(ap->pflags & ATA_PFLAG_FROZEN))
		@@ -6094,6 +6093,7 @@ void ata_host_init(struct ata_host host, struct device dev,
		{
		spin_lock_init(&host->lock);
		mutex_init(&host->eh_mutex);
		host->n_tags = ATA_MAX_QUEUE - 1;
		host->dev = dev;
		host->ops = ops;
		}
		@@ -6175,15 +6175,7 @@ int ata_host_register(struct ata_host host, struct scsi_host_template sht)
		{
		int i, rc;

		/*
		* The max queue supported by hardware must not be greater than
		* ATA_MAX_QUEUE.
		*/
		if (sht->can_queue > ATA_MAX_QUEUE) {
		dev_err(host->dev, "BUG: the hardware max queue is too large\n");
		WARN_ON(1);
		return -EINVAL;
		}
		host->n_tags = clamp(sht->can_queue, 1, ATA_MAX_QUEUE - 1);

		/* host must have been started */
		if (!(host->flags & ATA_HOST_STARTED)) {

include/linux/libata.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -593,6 +593,7 @@ struct ata_host {
		struct device *dev;
		void __iomem * const *iomap;
		unsigned int n_ports;
		unsigned int n_tags; /* nr of NCQ tags */
		void *private_data;
		struct ata_port_operations *ops;
		unsigned long flags;

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