[PATCH] libata: use preallocated buffers

It's not a very good idea to allocate memory during EH.  Use
statically allocated buffer for dev->id[] and add 512byte buffer
ap->sector_buf.  This buffer is owned by EH (or probing) and to be
used as temporary buffer for various purposes (IDENTIFY, NCQ log page
10h, PM GSCR block).

Signed-off-by: Tejun Heo <htejun@gmail.com>

2 files changed, 11 insertions, 25 deletions

diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 13bce43f1915..af55861a96e2 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -1099,7 +1099,7 @@ unsigned int ata_pio_need_iordy(const struct ata_device *adev)
  *      @dev: target device
  *      @p_class: pointer to class of the target device (may be changed)
  *      @post_reset: is this read ID post-reset?
- *      @p_id: read IDENTIFY page (newly allocated)
+ *      @id: buffer to read IDENTIFY data into
  *
  *      Read ID data from the specified device.  ATA_CMD_ID_ATA is
  *      performed on ATA devices and ATA_CMD_ID_ATAPI on ATAPI
@@ -1113,12 +1113,11 @@ unsigned int ata_pio_need_iordy(const struct ata_device *adev)
  *      0 on success, -errno otherwise.
  */
 static int ata_dev_read_id(struct ata_port *ap, struct ata_device *dev,
-                           unsigned int *p_class, int post_reset, u16 **p_id)
+                           unsigned int *p_class, int post_reset, u16 *id)
 {
         unsigned int class = *p_class;
         struct ata_taskfile tf;
         unsigned int err_mask = 0;
-        u16 *id;
         const char *reason;
         int rc;
 
@@ -1126,13 +1125,6 @@ static int ata_dev_read_id(struct ata_port *ap, struct ata_device *dev,
 
         ata_dev_select(ap, dev->devno, 1, 1); /* select device 0/1 */
 
-        id = kmalloc(sizeof(id[0]) * ATA_ID_WORDS, GFP_KERNEL);
-        if (id == NULL) {
-                rc = -ENOMEM;
-                reason = "out of memory";
-                goto err_out;
-        }
-
  retry:
         ata_tf_init(ap, &tf, dev->devno);
 
@@ -1194,13 +1186,12 @@ static int ata_dev_read_id(struct ata_port *ap, struct ata_device *dev,
         }
 
         *p_class = class;
-        *p_id = id;
+
         return 0;
 
  err_out:
         printk(KERN_WARNING "ata%u: dev %u failed to IDENTIFY (%s)\n",
                ap->id, dev->devno, reason);
-        kfree(id);
         return rc;
 }
 
@@ -1425,9 +1416,7 @@ static int ata_bus_probe(struct ata_port *ap)
                 if (!ata_dev_enabled(dev))
                         continue;
 
-                kfree(dev->id);
-                dev->id = NULL;
-                rc = ata_dev_read_id(ap, dev, &dev->class, 1, &dev->id);
+                rc = ata_dev_read_id(ap, dev, &dev->class, 1, dev->id);
                 if (rc)
                         goto fail;
 
@@ -2788,7 +2777,7 @@ int ata_dev_revalidate(struct ata_port *ap, struct ata_device *dev,
                        int post_reset)
 {
         unsigned int class = dev->class;
-        u16 *id = NULL;
+        u16 *id = (void *)ap->sector_buf;
         int rc;
 
         if (!ata_dev_enabled(dev)) {
@@ -2796,8 +2785,8 @@ int ata_dev_revalidate(struct ata_port *ap, struct ata_device *dev,
                 goto fail;
         }
 
-        /* allocate & read ID data */
-        rc = ata_dev_read_id(ap, dev, &class, post_reset, &id);
+        /* read ID data */
+        rc = ata_dev_read_id(ap, dev, &class, post_reset, id);
         if (rc)
                 goto fail;
 
@@ -2807,8 +2796,7 @@ int ata_dev_revalidate(struct ata_port *ap, struct ata_device *dev,
                 goto fail;
         }
 
-        kfree(dev->id);
-        dev->id = id;
+        memcpy(dev->id, id, sizeof(id[0]) * ATA_ID_WORDS);
 
         /* configure device according to the new ID */
         rc = ata_dev_configure(ap, dev, 0);
@@ -2818,7 +2806,6 @@ int ata_dev_revalidate(struct ata_port *ap, struct ata_device *dev,
  fail:
         printk(KERN_ERR "ata%u: dev %u revalidation failed (errno=%d)\n",
                ap->id, dev->devno, rc);
-        kfree(id);
         return rc;
 }
 
@@ -4873,14 +4860,11 @@ void ata_host_set_remove(struct ata_host_set *host_set)
 int ata_scsi_release(struct Scsi_Host *host)
 {
         struct ata_port *ap = ata_shost_to_port(host);
-        int i;
 
         DPRINTK("ENTER\n");
 
         ap->ops->port_disable(ap);
         ata_host_remove(ap, 0);
-        for (i = 0; i < ATA_MAX_DEVICES; i++)
-                kfree(ap->device[i].id);
 
         DPRINTK("EXIT\n");
         return 1;
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 220b9d7bfc28..0e1a3be39475 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -360,7 +360,7 @@ struct ata_device {
         unsigned long           flags;          /* ATA_DFLAG_xxx */
         unsigned int            class;          /* ATA_DEV_xxx */
         unsigned int            devno;          /* 0 or 1 */
-        u16                     *id;            /* IDENTIFY xxx DEVICE data */
+        u16                     id[ATA_ID_WORDS]; /* IDENTIFY xxx DEVICE data */
         u8                      pio_mode;
         u8                      dma_mode;
         u8                      xfer_mode;
@@ -425,6 +425,8 @@ struct ata_port {
         struct list_head        eh_done_q;
 
         void                    *private_data;
+
+        u8                      sector_buf[ATA_SECT_SIZE]; /* owned by EH */
 };
 
 struct ata_port_operations {