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Subject[patch 4/6] ide: allow ide_dev_read_id() to be called from the IRQ context
Date
From: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Subject: [PATCH] ide: allow ide_dev_read_id() to be called from the IRQ context

* Un-static __ide_wait_stat().

* Allow ide_dev_read_id() helper to be called from the IRQ context by
adding irq_ctx flag and using mdelay()/__ide_wait_stat() when needed.

* Switch ide_driveid_update() to set irq_ctx flag.

This change is needed for the consecutive patch which fixes races in
handling of user-space SET XFER commands but for improved bisectability
and clarity it is better to do it in a separate patch.

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
---
I'm not completely happy with this version of patch since I originally
intended to unify ide_busy_sleep() with __ide_wait_stat() first..
drivers/ide/ide-iops.c | 6 +++---
drivers/ide/ide-probe.c | 31 +++++++++++++++++++++----------
include/linux/ide.h | 3 ++-
3 files changed, 26 insertions(+), 14 deletions(-)
Index: b/drivers/ide/ide-iops.c
===================================================================
--- a/drivers/ide/ide-iops.c
+++ b/drivers/ide/ide-iops.c
@@ -102,8 +102,8 @@ EXPORT_SYMBOL(ide_fixstring);
* setting a timer to wake up at half second intervals thereafter,
* until timeout is achieved, before timing out.
*/
-static int __ide_wait_stat(ide_drive_t *drive, u8 good, u8 bad,
- unsigned long timeout, u8 *rstat)
+int __ide_wait_stat(ide_drive_t *drive, u8 good, u8 bad,
+ unsigned long timeout, u8 *rstat)
{
ide_hwif_t *hwif = drive->hwif;
const struct ide_tp_ops *tp_ops = hwif->tp_ops;
@@ -316,7 +316,7 @@ int ide_driveid_update(ide_drive_t *driv
return 0;

SELECT_MASK(drive, 1);
- rc = ide_dev_read_id(drive, ATA_CMD_ID_ATA, id);
+ rc = ide_dev_read_id(drive, ATA_CMD_ID_ATA, id, 1);
SELECT_MASK(drive, 0);

if (rc)
Index: b/drivers/ide/ide-probe.c
===================================================================
--- a/drivers/ide/ide-probe.c
+++ b/drivers/ide/ide-probe.c
@@ -238,6 +238,7 @@ static void do_identify(ide_drive_t *dri
* @drive: drive to identify
* @cmd: command to use
* @id: buffer for IDENTIFY data
+ * @irq_ctx: flag set when called from the IRQ context
*
* Sends an ATA(PI) IDENTIFY request to a drive and waits for a response.
*
@@ -246,7 +247,7 @@ static void do_identify(ide_drive_t *dri
* 2 device aborted the command (refused to identify itself)
*/

-int ide_dev_read_id(ide_drive_t *drive, u8 cmd, u16 *id)
+int ide_dev_read_id(ide_drive_t *drive, u8 cmd, u16 *id, int irq_ctx)
{
ide_hwif_t *hwif = drive->hwif;
struct ide_io_ports *io_ports = &hwif->io_ports;
@@ -263,7 +264,10 @@ int ide_dev_read_id(ide_drive_t *drive,
tp_ops->write_devctl(hwif, ATA_NIEN | ATA_DEVCTL_OBS);

/* take a deep breath */
- msleep(50);
+ if (irq_ctx)
+ mdelay(50);
+ else
+ msleep(50);

if (io_ports->ctl_addr &&
(hwif->host_flags & IDE_HFLAG_BROKEN_ALTSTATUS) == 0) {
@@ -295,12 +299,19 @@ int ide_dev_read_id(ide_drive_t *drive,

timeout = ((cmd == ATA_CMD_ID_ATA) ? WAIT_WORSTCASE : WAIT_PIDENTIFY) / 2;

- if (ide_busy_sleep(drive, timeout, use_altstatus))
- return 1;
-
/* wait for IRQ and ATA_DRQ */
- msleep(50);
- s = tp_ops->read_status(hwif);
+ if (irq_ctx) {
+ rc = __ide_wait_stat(drive, ATA_DRQ, BAD_R_STAT, timeout, &s);
+ if (rc)
+ return 1;
+ } else {
+ rc = ide_busy_sleep(drive, timeout, use_altstatus);
+ if (rc)
+ return 1;
+
+ msleep(50);
+ s = tp_ops->read_status(hwif);
+ }

if (OK_STAT(s, ATA_DRQ, BAD_R_STAT)) {
/* drive returned ID */
@@ -406,10 +417,10 @@ static int do_probe (ide_drive_t *drive,

if (OK_STAT(stat, ATA_DRDY, ATA_BUSY) ||
present || cmd == ATA_CMD_ID_ATAPI) {
- rc = ide_dev_read_id(drive, cmd, id);
+ rc = ide_dev_read_id(drive, cmd, id, 0);
if (rc)
/* failed: try again */
- rc = ide_dev_read_id(drive, cmd, id);
+ rc = ide_dev_read_id(drive, cmd, id, 0);

stat = tp_ops->read_status(hwif);

@@ -424,7 +435,7 @@ static int do_probe (ide_drive_t *drive,
msleep(50);
tp_ops->exec_command(hwif, ATA_CMD_DEV_RESET);
(void)ide_busy_sleep(drive, WAIT_WORSTCASE, 0);
- rc = ide_dev_read_id(drive, cmd, id);
+ rc = ide_dev_read_id(drive, cmd, id, 0);
}

/* ensure drive IRQ is clear */
Index: b/include/linux/ide.h
===================================================================
--- a/include/linux/ide.h
+++ b/include/linux/ide.h
@@ -1081,6 +1081,7 @@ extern void ide_fixstring(u8 *, const in

int ide_busy_sleep(ide_drive_t *, unsigned long, int);

+int __ide_wait_stat(ide_drive_t *, u8, u8, unsigned long, u8 *);
int ide_wait_stat(ide_startstop_t *, ide_drive_t *, u8, u8, unsigned long);

ide_startstop_t ide_do_park_unpark(ide_drive_t *, struct request *);
@@ -1169,7 +1170,7 @@ int ide_no_data_taskfile(ide_drive_t *,

int ide_taskfile_ioctl(ide_drive_t *, unsigned long);

-int ide_dev_read_id(ide_drive_t *, u8, u16 *);
+int ide_dev_read_id(ide_drive_t *, u8, u16 *, int);

extern int ide_driveid_update(ide_drive_t *);
extern int ide_config_drive_speed(ide_drive_t *, u8);

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