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linux_dsm_epyc7002/drivers/ata/libata.h
Tejun Heo c0c362b60e libata: implement cross-port EH exclusion 
In libata, the non-EH code paths should always take and release
ap->lock explicitly when accessing hardware or shared data structures.
However, once EH is active, it's assumed that the port is owned by EH
and EH methods don't explicitly take ap->lock unless race from irq
handler or other code paths are expected.  However, libata EH didn't
guarantee exclusion among EHs for ports of the same host.  IOW,
multiple EHs may execute in parallel on multiple ports of the same
controller.

In many cases, especially in SATA, the ports are completely
independent of each other and this doesn't cause problems; however,
there are cases where different ports share the same resource, which
lead to obscure timing related bugs such as the one fixed by commit
213373cf (ata_piix: fix locking around SIDPR access).

This patch implements exclusion among EHs of the same host.  When EH
begins, it acquires per-host EH ownership by calling ata_eh_acquire().
When EH finishes, the ownership is released by calling
ata_eh_release().  EH ownership is also released whenever the EH
thread goes to sleep from ata_msleep() or explicitly and reacquired
after waking up.

This ensures that while EH is actively accessing the hardware, it has
exclusive access to it while allowing EHs to interleave and progress
in parallel as they hit waiting stages, which dominate the time spent
in EH.  This achieves cross-port EH exclusion without pervasive and
fragile changes while still allowing parallel EH for the most part.

This was first reported by yuanding02@gmail.com more than three years
ago in the following bugzilla.  :-)

  https://bugzilla.kernel.org/show_bug.cgi?id=8223

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Reported-by: yuanding02@gmail.com
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
2010-10-21 20:21:05 -04:00

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/*
* libata.h - helper library for ATA
*
* Copyright 2003-2004 Red Hat, Inc. All rights reserved.
* Copyright 2003-2004 Jeff Garzik
*
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; see the file COPYING. If not, write to
* the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
*
*
* libata documentation is available via 'make {ps|pdf}docs',
* as Documentation/DocBook/libata.*
*
*/
#ifndef __LIBATA_H__
#define __LIBATA_H__
#define DRV_NAME "libata"
#define DRV_VERSION "3.00" /* must be exactly four chars */
struct ata_scsi_args {
struct ata_device *dev;
u16 *id;
struct scsi_cmnd *cmd;
void (*done)(struct scsi_cmnd *);
};
/* libata-core.c */
enum {
/* flags for ata_dev_read_id() */
ATA_READID_POSTRESET = (1 << 0), /* reading ID after reset */
/* selector for ata_down_xfermask_limit() */
ATA_DNXFER_PIO = 0, /* speed down PIO */
ATA_DNXFER_DMA = 1, /* speed down DMA */
ATA_DNXFER_40C = 2, /* apply 40c cable limit */
ATA_DNXFER_FORCE_PIO = 3, /* force PIO */
ATA_DNXFER_FORCE_PIO0 = 4, /* force PIO0 */
ATA_DNXFER_QUIET = (1 << 31),
};
extern unsigned int ata_print_id;
extern int atapi_passthru16;
extern int libata_fua;
extern int libata_noacpi;
extern int libata_allow_tpm;
extern struct ata_link *ata_dev_phys_link(struct ata_device *dev);
extern void ata_force_cbl(struct ata_port *ap);
extern u64 ata_tf_to_lba(const struct ata_taskfile *tf);
extern u64 ata_tf_to_lba48(const struct ata_taskfile *tf);
extern struct ata_queued_cmd *ata_qc_new_init(struct ata_device *dev);
extern int ata_build_rw_tf(struct ata_taskfile *tf, struct ata_device *dev,
u64 block, u32 n_block, unsigned int tf_flags,
unsigned int tag);
extern u64 ata_tf_read_block(struct ata_taskfile *tf, struct ata_device *dev);
extern unsigned ata_exec_internal(struct ata_device *dev,
struct ata_taskfile *tf, const u8 *cdb,
int dma_dir, void *buf, unsigned int buflen,
unsigned long timeout);
extern unsigned ata_exec_internal_sg(struct ata_device *dev,
struct ata_taskfile *tf, const u8 *cdb,
int dma_dir, struct scatterlist *sg,
unsigned int n_elem, unsigned long timeout);
extern unsigned int ata_do_simple_cmd(struct ata_device *dev, u8 cmd);
extern int ata_wait_ready(struct ata_link *link, unsigned long deadline,
int (*check_ready)(struct ata_link *link));
extern int ata_dev_read_id(struct ata_device *dev, unsigned int *p_class,
unsigned int flags, u16 *id);
extern int ata_dev_reread_id(struct ata_device *dev, unsigned int readid_flags);
extern int ata_dev_revalidate(struct ata_device *dev, unsigned int new_class,
unsigned int readid_flags);
extern int ata_dev_configure(struct ata_device *dev);
extern int sata_down_spd_limit(struct ata_link *link, u32 spd_limit);
extern int ata_down_xfermask_limit(struct ata_device *dev, unsigned int sel);
extern unsigned int ata_dev_set_feature(struct ata_device *dev,
u8 enable, u8 feature);
extern void ata_sg_clean(struct ata_queued_cmd *qc);
extern void ata_qc_free(struct ata_queued_cmd *qc);
extern void ata_qc_issue(struct ata_queued_cmd *qc);
extern void __ata_qc_complete(struct ata_queued_cmd *qc);
extern int atapi_check_dma(struct ata_queued_cmd *qc);
extern void swap_buf_le16(u16 *buf, unsigned int buf_words);
extern bool ata_phys_link_online(struct ata_link *link);
extern bool ata_phys_link_offline(struct ata_link *link);
extern void ata_dev_init(struct ata_device *dev);
extern void ata_link_init(struct ata_port *ap, struct ata_link *link, int pmp);
extern int sata_link_init_spd(struct ata_link *link);
extern int ata_task_ioctl(struct scsi_device *scsidev, void __user *arg);
extern int ata_cmd_ioctl(struct scsi_device *scsidev, void __user *arg);
extern struct ata_port *ata_port_alloc(struct ata_host *host);
extern const char *sata_spd_string(unsigned int spd);
/* libata-acpi.c */
#ifdef CONFIG_ATA_ACPI
extern unsigned int ata_acpi_gtf_filter;
extern void ata_acpi_associate_sata_port(struct ata_port *ap);
extern void ata_acpi_associate(struct ata_host *host);
extern void ata_acpi_dissociate(struct ata_host *host);
extern int ata_acpi_on_suspend(struct ata_port *ap);
extern void ata_acpi_on_resume(struct ata_port *ap);
extern int ata_acpi_on_devcfg(struct ata_device *dev);
extern void ata_acpi_on_disable(struct ata_device *dev);
extern void ata_acpi_set_state(struct ata_port *ap, pm_message_t state);
#else
static inline void ata_acpi_associate_sata_port(struct ata_port *ap) { }
static inline void ata_acpi_associate(struct ata_host *host) { }
static inline void ata_acpi_dissociate(struct ata_host *host) { }
static inline int ata_acpi_on_suspend(struct ata_port *ap) { return 0; }
static inline void ata_acpi_on_resume(struct ata_port *ap) { }
static inline int ata_acpi_on_devcfg(struct ata_device *dev) { return 0; }
static inline void ata_acpi_on_disable(struct ata_device *dev) { }
static inline void ata_acpi_set_state(struct ata_port *ap,
pm_message_t state) { }
#endif
/* libata-scsi.c */
extern int ata_scsi_add_hosts(struct ata_host *host,
struct scsi_host_template *sht);
extern void ata_scsi_scan_host(struct ata_port *ap, int sync);
extern int ata_scsi_offline_dev(struct ata_device *dev);
extern void ata_scsi_media_change_notify(struct ata_device *dev);
extern void ata_scsi_hotplug(struct work_struct *work);
extern void ata_schedule_scsi_eh(struct Scsi_Host *shost);
extern void ata_scsi_dev_rescan(struct work_struct *work);
extern int ata_bus_probe(struct ata_port *ap);
extern int ata_scsi_user_scan(struct Scsi_Host *shost, unsigned int channel,
unsigned int id, unsigned int lun);
/* libata-eh.c */
extern unsigned long ata_internal_cmd_timeout(struct ata_device *dev, u8 cmd);
extern void ata_internal_cmd_timed_out(struct ata_device *dev, u8 cmd);
extern void ata_eh_acquire(struct ata_port *ap);
extern void ata_eh_release(struct ata_port *ap);
extern enum blk_eh_timer_return ata_scsi_timed_out(struct scsi_cmnd *cmd);
extern void ata_scsi_error(struct Scsi_Host *host);
extern void ata_port_wait_eh(struct ata_port *ap);
extern void ata_eh_fastdrain_timerfn(unsigned long arg);
extern void ata_qc_schedule_eh(struct ata_queued_cmd *qc);
extern void ata_dev_disable(struct ata_device *dev);
extern void ata_eh_detach_dev(struct ata_device *dev);
extern void ata_eh_about_to_do(struct ata_link *link, struct ata_device *dev,
unsigned int action);
extern void ata_eh_done(struct ata_link *link, struct ata_device *dev,
unsigned int action);
extern void ata_eh_autopsy(struct ata_port *ap);
const char *ata_get_cmd_descript(u8 command);
extern void ata_eh_report(struct ata_port *ap);
extern int ata_eh_reset(struct ata_link *link, int classify,
ata_prereset_fn_t prereset, ata_reset_fn_t softreset,
ata_reset_fn_t hardreset, ata_postreset_fn_t postreset);
extern int ata_set_mode(struct ata_link *link, struct ata_device **r_failed_dev);
extern int ata_eh_recover(struct ata_port *ap, ata_prereset_fn_t prereset,
ata_reset_fn_t softreset, ata_reset_fn_t hardreset,
ata_postreset_fn_t postreset,
struct ata_link **r_failed_disk);
extern void ata_eh_finish(struct ata_port *ap);
extern int ata_ering_map(struct ata_ering *ering,
int (*map_fn)(struct ata_ering_entry *, void *),
void *arg);
/* libata-pmp.c */
#ifdef CONFIG_SATA_PMP
extern int sata_pmp_scr_read(struct ata_link *link, int reg, u32 *val);
extern int sata_pmp_scr_write(struct ata_link *link, int reg, u32 val);
extern int sata_pmp_set_lpm(struct ata_link *link, enum ata_lpm_policy policy,
unsigned hints);
extern int sata_pmp_attach(struct ata_device *dev);
#else /* CONFIG_SATA_PMP */
static inline int sata_pmp_scr_read(struct ata_link *link, int reg, u32 *val)
{
return -EINVAL;
}
static inline int sata_pmp_scr_write(struct ata_link *link, int reg, u32 val)
{
return -EINVAL;
}
static inline int sata_pmp_set_lpm(struct ata_link *link,
enum ata_lpm_policy policy, unsigned hints)
{
return -EINVAL;
}
static inline int sata_pmp_attach(struct ata_device *dev)
{
return -EINVAL;
}
#endif /* CONFIG_SATA_PMP */
/* libata-sff.c */
#ifdef CONFIG_ATA_SFF
extern void ata_sff_flush_pio_task(struct ata_port *ap);
extern void ata_sff_port_init(struct ata_port *ap);
extern int ata_sff_init(void);
extern void ata_sff_exit(void);
#else /* CONFIG_ATA_SFF */
static inline void ata_sff_flush_pio_task(struct ata_port *ap)
{ }
static inline void ata_sff_port_init(struct ata_port *ap)
{ }
static inline int ata_sff_init(void)
{ return 0; }
static inline void ata_sff_exit(void)
{ }
#endif /* CONFIG_ATA_SFF */
#endif /* __LIBATA_H__ */
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