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scsi: mac_esp: Replace bogus memory barrier with spinlock 

Commit da244654c6 ("[SCSI] mac_esp: fix for quadras with two esp
chips") added mac_scsi_esp_intr() to handle the IRQ lines from a pair of
on-board ESP chips (a normal shared IRQ did not work).

Proper mutual exclusion was missing from that patch. This patch fixes
race conditions between comparison and assignment of esp_chips[]
pointers.

Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Finn Thain 2017-04-02 17:08:05 +10:00 committed by Martin K. Petersen
parent 62d57f20ff
commit 4da2b1eb23
1 changed files with 23 additions and 10 deletions
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33
drivers/scsi/mac_esp.c
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@ -55,6 +55,7 @@ struct mac_esp_priv {
int error;
};
static struct esp *esp_chips[2];
static DEFINE_SPINLOCK(esp_chips_lock);
#define MAC_ESP_GET_PRIV(esp) ((struct mac_esp_priv *) \
platform_get_drvdata((struct platform_device *) \
@ -562,15 +563,18 @@ static int esp_mac_probe(struct platform_device *dev)
}
host->irq = IRQ_MAC_SCSI;
esp_chips[dev->id] = esp;
mb();
if (esp_chips[!dev->id] == NULL) {
err = request_irq(host->irq, mac_scsi_esp_intr, 0, "ESP", NULL);
if (err < 0) {
esp_chips[dev->id] = NULL;
goto fail_free_priv;
}
/* The request_irq() call is intended to succeed for the first device
* and fail for the second device.
*/
err = request_irq(host->irq, mac_scsi_esp_intr, 0, "ESP", NULL);
spin_lock(&esp_chips_lock);
if (err < 0 && esp_chips[!dev->id] == NULL) {
spin_unlock(&esp_chips_lock);
goto fail_free_priv;
}
esp_chips[dev->id] = esp;
spin_unlock(&esp_chips_lock);
err = scsi_esp_register(esp, &dev->dev);
if (err)
@ -579,8 +583,13 @@ static int esp_mac_probe(struct platform_device *dev)
return 0;
fail_free_irq:
if (esp_chips[!dev->id] == NULL)
spin_lock(&esp_chips_lock);
esp_chips[dev->id] = NULL;
if (esp_chips[!dev->id] == NULL) {
spin_unlock(&esp_chips_lock);
free_irq(host->irq, esp);
} else
spin_unlock(&esp_chips_lock);
fail_free_priv:
kfree(mep);
fail_free_command_block:
@ -599,9 +608,13 @@ static int esp_mac_remove(struct platform_device *dev)
scsi_esp_unregister(esp);
spin_lock(&esp_chips_lock);
esp_chips[dev->id] = NULL;
if (!(esp_chips[0] || esp_chips[1]))
if (esp_chips[!dev->id] == NULL) {
spin_unlock(&esp_chips_lock);
free_irq(irq, NULL);
} else
spin_unlock(&esp_chips_lock);
kfree(mep);