linux.git/drivers/ata/libata-core.c, branch v2.6.37 Linux kernel source tree libata: no special completion processing for EH commands 2010-12-24T18:34:18+00:00 Tejun Heo tj@kernel.org 2010-12-09T14:59:32+00:00 f08dc1ac6b15c681f4643d8da1700e06c3855608 ata_qc_complete() contains special handling for certain commands. For example, it schedules EH for device revalidation after certain configurations are changed. These shouldn't be applied to EH commands but they were. In most cases, it doesn't cause an actual problem because EH doesn't issue any command which would trigger special handling; however, ACPI can issue such commands via _GTF which can cause weird interactions. Restructure ata_qc_complete() such that EH commands are always passed on to __ata_qc_complete(). stable: Please apply to -stable only after 2.6.38 is released. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Kyle McMartin <kyle@mcmartin.ca> Cc: stable@kernel.org Signed-off-by: Jeff Garzik <jgarzik@redhat.com> 
ata_qc_complete() contains special handling for certain commands.  For
example, it schedules EH for device revalidation after certain
configurations are changed.  These shouldn't be applied to EH
commands but they were.

In most cases, it doesn't cause an actual problem because EH doesn't
issue any command which would trigger special handling; however, ACPI
can issue such commands via _GTF which can cause weird interactions.

Restructure ata_qc_complete() such that EH commands are always passed
on to __ata_qc_complete().

stable: Please apply to -stable only after 2.6.38 is released.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Kyle McMartin <kyle@mcmartin.ca>
Cc: stable@kernel.org
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
libata: implement cross-port EH exclusion 2010-10-22T00:21:05+00:00 Tejun Heo htejun@gmail.com 2010-09-06T15:57:14+00:00 c0c362b60e259e3480a36ef70280d545818844f0 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> 
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>
libata: add @ap to ata_wait_register() and introduce ata_msleep() 2010-10-22T00:21:05+00:00 Tejun Heo tj@kernel.org 2010-09-06T15:56:29+00:00 97750cebb3000a9cc08f8ce8dc8c7143be7d7201 Add optional @ap argument to ata_wait_register() and replace msleep() calls with ata_msleep() which take optional @ap in addition to the duration. These will be used to implement EH exclusion. This patch doesn't cause any behavior difference. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jeff Garzik <jgarzik@redhat.com> 
Add optional @ap argument to ata_wait_register() and replace msleep()
calls with ata_msleep() which take optional @ap in addition to the
duration.  These will be used to implement EH exclusion.

This patch doesn't cause any behavior difference.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
libata: reimplement link power management 2010-10-22T00:21:04+00:00 Tejun Heo tj@kernel.org 2010-09-01T15:50:06+00:00 6b7ae9545ad9875a289f4191c0216b473e313cb9 The current LPM implementation has the following issues. * Operation order isn't well thought-out. e.g. HIPM should be configured after IPM in SControl is properly configured. Not the other way around. * Suspend/resume paths call ata_lpm_enable/disable() which must only be called from EH context directly. Also, ata_lpm_enable/disable() were called whether LPM was in use or not. * Implementation is per-port when it should be per-link. As a result, it can't be used for controllers with slave links or PMP. * LPM state isn't managed consistently. After a link reset for whatever reason including suspend/resume the actual LPM state would be reset leaving ap->lpm_policy inconsistent. * Generic/driver-specific logic boundary isn't clear. Currently, libahci has to mangle stuff which libata EH proper should be handling. This makes the implementation unnecessarily complex and fragile. * Tied to ALPM. Doesn't consider DIPM only cases and doesn't check whether the device allows HIPM. * Error handling isn't implemented. Given the extent of mismatch with the rest of libata, I don't think trying to fix it piecewise makes much sense. This patch reimplements LPM support. * The new implementation is per-link. The target policy is still port-wide (ap->target_lpm_policy) but all the mechanisms and states are per-link and integrate well with the rest of link abstraction and can work with slave and PMP links. * Core EH has proper control of LPM state. LPM state is reconfigured when and only when reconfiguration is necessary. It makes sure that LPM state is reset when probing for new device on the link. Controller agnostic logic is now implemented in libata EH proper and driver implementation only has to deal with controller specifics. * Proper error handling. LPM config failure is attributed to the device on the link and LPM is disabled for the link if it fails repeatedly. * ops->enable/disable_pm() are replaced with single ops->set_lpm() which takes @policy and @hints. This simplifies driver specific implementation. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jeff Garzik <jgarzik@redhat.com> 
The current LPM implementation has the following issues.

* Operation order isn't well thought-out.  e.g. HIPM should be
  configured after IPM in SControl is properly configured.  Not the
  other way around.

* Suspend/resume paths call ata_lpm_enable/disable() which must only
  be called from EH context directly.  Also, ata_lpm_enable/disable()
  were called whether LPM was in use or not.

* Implementation is per-port when it should be per-link.  As a result,
  it can't be used for controllers with slave links or PMP.

* LPM state isn't managed consistently.  After a link reset for
  whatever reason including suspend/resume the actual LPM state would
  be reset leaving ap->lpm_policy inconsistent.

* Generic/driver-specific logic boundary isn't clear.  Currently,
  libahci has to mangle stuff which libata EH proper should be
  handling.  This makes the implementation unnecessarily complex and
  fragile.

* Tied to ALPM.  Doesn't consider DIPM only cases and doesn't check
  whether the device allows HIPM.

* Error handling isn't implemented.

Given the extent of mismatch with the rest of libata, I don't think
trying to fix it piecewise makes much sense.  This patch reimplements
LPM support.

* The new implementation is per-link.  The target policy is still
  port-wide (ap->target_lpm_policy) but all the mechanisms and states
  are per-link and integrate well with the rest of link abstraction
  and can work with slave and PMP links.

* Core EH has proper control of LPM state.  LPM state is reconfigured
  when and only when reconfiguration is necessary.  It makes sure that
  LPM state is reset when probing for new device on the link.
  Controller agnostic logic is now implemented in libata EH proper and
  driver implementation only has to deal with controller specifics.

* Proper error handling.  LPM config failure is attributed to the
  device on the link and LPM is disabled for the link if it fails
  repeatedly.

* ops->enable/disable_pm() are replaced with single ops->set_lpm()
  which takes @policy and @hints.  This simplifies driver specific
  implementation.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
libata: implement sata_link_scr_lpm() and make ata_dev_set_feature() global 2010-10-22T00:21:04+00:00 Tejun Heo tj@kernel.org 2010-09-01T15:50:05+00:00 1152b2617a6e1943b6b82e07c962950e56f1000c Link power management is about to be reimplemented. Prepare for it. * Implement sata_link_scr_lpm(). * Drop static from ata_dev_set_feature() and make it available to other libata files. * Trivial whitespace adjustments. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jeff Garzik <jgarzik@redhat.com> 
Link power management is about to be reimplemented.  Prepare for it.

* Implement sata_link_scr_lpm().

* Drop static from ata_dev_set_feature() and make it available to
  other libata files.

* Trivial whitespace adjustments.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
libata: clean up lpm related symbols and sysfs show/store functions 2010-10-22T00:21:04+00:00 Tejun Heo tj@kernel.org 2010-09-01T15:50:04+00:00 c93b263e0d4fa8ce5fec0142a98196d1a127e845 Link power management related symbols are in confusing state w/ mixed usages of lpm, ipm and pm. This patch cleans up lpm related symbols and sysfs show/store functions as follows. * lpm states - NOT_AVAILABLE, MIN_POWER, MAX_PERFORMANCE and MEDIUM_POWER are renamed to ATA_LPM_UNKNOWN and ATA_LPM_{MIN|MAX|MED}_POWER. * Pre/postfixes are unified to lpm. * sysfs show/store functions for link_power_management_policy were curiously named get/put and unnecessarily complex. Renamed to show/store and simplified. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jeff Garzik <jgarzik@redhat.com> 
Link power management related symbols are in confusing state w/ mixed
usages of lpm, ipm and pm.  This patch cleans up lpm related symbols
and sysfs show/store functions as follows.

* lpm states - NOT_AVAILABLE, MIN_POWER, MAX_PERFORMANCE and
  MEDIUM_POWER are renamed to ATA_LPM_UNKNOWN and
  ATA_LPM_{MIN|MAX|MED}_POWER.

* Pre/postfixes are unified to lpm.

* sysfs show/store functions for link_power_management_policy were
  curiously named get/put and unnecessarily complex.  Renamed to
  show/store and simplified.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
libata: always use ata_qc_complete_multiple() for NCQ command completions 2010-10-22T00:21:03+00:00 Tejun Heo tj@kernel.org 2010-06-25T13:03:34+00:00 1aadf5c3bbbbb0db09dcb5aa26c61326e0d3e9e7 Currently, sata_fsl, mv and nv call ata_qc_complete() multiple times from their interrupt handlers to indicate completion of NCQ commands. This limits the visibility the libata core layer has into how commands are being executed and completed, which is necessary to support IRQ expecting in generic way. libata already has an interface to complete multiple commands at once - ata_qc_complete_multiple() which ahci and sata_sil24 already use. This patch updates the three drivers to use ata_qc_complete_multiple() too and updates comments on ata_qc_complete[_multiple]() regarding their usages with NCQ completions. This change not only provides better visibility into command execution to the core layer but also simplifies low level drivers. * sata_fsl: It already builds done_mask. Conversion is straight forward. * sata_mv: mv_process_crpb_response() no longer checks for illegal completions, it just returns whether the tag is completed or not. mv_process_crpb_entries() builds done_mask from it and passes it to ata_qc_complete_multiple() which will check for illegal completions. * sata_nv adma: Similar to sata_mv. nv_adma_check_cpb() now just returns the tag status and nv_adma_interrupt() builds done_mask from it and passes it to ata_qc_complete_multiple(). * sata_nv swncq: It already builds done_mask. Drop unnecessary illegal transition checks and call ata_qc_complete_multiple(). In the long run, it might be a good idea to make ata_qc_complete() whine if called when multiple NCQ commands are in flight. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ashish Kalra <ashish.kalra@freescale.com> Cc: Saeed Bishara <saeed@marvell.com> Cc: Mark Lord <liml@rtr.ca> Cc: Robert Hancock <hancockr@shaw.ca> Signed-off-by: Jeff Garzik <jgarzik@redhat.com> 
Currently, sata_fsl, mv and nv call ata_qc_complete() multiple times
from their interrupt handlers to indicate completion of NCQ commands.
This limits the visibility the libata core layer has into how commands
are being executed and completed, which is necessary to support IRQ
expecting in generic way.  libata already has an interface to complete
multiple commands at once - ata_qc_complete_multiple() which ahci and
sata_sil24 already use.

This patch updates the three drivers to use ata_qc_complete_multiple()
too and updates comments on ata_qc_complete[_multiple]() regarding
their usages with NCQ completions.  This change not only provides
better visibility into command execution to the core layer but also
simplifies low level drivers.

* sata_fsl: It already builds done_mask.  Conversion is straight
  forward.

* sata_mv: mv_process_crpb_response() no longer checks for illegal
  completions, it just returns whether the tag is completed or not.
  mv_process_crpb_entries() builds done_mask from it and passes it to
  ata_qc_complete_multiple() which will check for illegal completions.

* sata_nv adma: Similar to sata_mv.  nv_adma_check_cpb() now just
  returns the tag status and nv_adma_interrupt() builds done_mask from
  it and passes it to ata_qc_complete_multiple().

* sata_nv swncq: It already builds done_mask.  Drop unnecessary
  illegal transition checks and call ata_qc_complete_multiple().

In the long run, it might be a good idea to make ata_qc_complete()
whine if called when multiple NCQ commands are in flight.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Ashish Kalra <ashish.kalra@freescale.com>
Cc: Saeed Bishara <saeed@marvell.com>
Cc: Mark Lord <liml@rtr.ca>
Cc: Robert Hancock <hancockr@shaw.ca>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
[libata] Add ATA transport class 2010-10-22T00:21:03+00:00 Gwendal Grignou gwendal@google.com 2010-05-25T19:31:38+00:00 d9027470b88631d0956ac37cdadfdeb9cdcf2c99 This is a scheleton for libata transport class. All information is read only, exporting information from libata: - ata_port class: one per ATA port - ata_link class: one per ATA port or 15 for SATA Port Multiplier - ata_device class: up to 2 for PATA link, usually one for SATA. Signed-off-by: Gwendal Grignou <gwendal@google.com> Reviewed-by: Grant Grundler <grundler@google.com> Signed-off-by: Jeff Garzik <jgarzik@redhat.com> 
This is a scheleton for libata transport class.
All information is read only, exporting information from libata:
- ata_port class: one per ATA port
- ata_link class: one per ATA port or 15 for SATA Port Multiplier
- ata_device class: up to 2 for PATA link, usually one for SATA.

Signed-off-by: Gwendal Grignou <gwendal@google.com>
Reviewed-by: Grant Grundler <grundler@google.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
libata: skip EH autopsy and recovery during suspend 2010-09-10T02:27:59+00:00 Tejun Heo htejun@gmail.com 2010-09-07T12:05:31+00:00 e2f3d75fc0e4a0d03c61872bad39ffa2e74a04ff For some mysterious reason, certain hardware reacts badly to usual EH actions while the system is going for suspend. As the devices won't be needed until the system is resumed, ask EH to skip usual autopsy and recovery and proceed directly to suspend. Signed-off-by: Tejun Heo <tj@kernel.org> Tested-by: Stephan Diestelhorst <stephan.diestelhorst@amd.com> Cc: stable@kernel.org Signed-off-by: Jeff Garzik <jgarzik@redhat.com> 
For some mysterious reason, certain hardware reacts badly to usual EH
actions while the system is going for suspend.  As the devices won't
be needed until the system is resumed, ask EH to skip usual autopsy
and recovery and proceed directly to suspend.

Signed-off-by: Tejun Heo <tj@kernel.org>
Tested-by: Stephan Diestelhorst <stephan.diestelhorst@amd.com>
Cc: stable@kernel.org
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
libata: be less of a drama queen on empty data commands 2010-08-25T23:24:16+00:00 Tejun Heo tj@kernel.org 2010-08-23T09:27:27+00:00 60f5d6ef6b6e70fe850554381fd8336f11530002 ata_qc_issue() BUG_ON()s on data commands w/o data, which may be submitted via SG_IO. Be less of a drama queen and just trigger WARN_ON_ONCE() and fail the command with AC_ERR_SYSTEM. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Stefan Hübner <stefan.huebner@stud.tu-ilmenau.de> Signed-off-by: Jeff Garzik <jgarzik@redhat.com> 
ata_qc_issue() BUG_ON()s on data commands w/o data, which may be
submitted via SG_IO.  Be less of a drama queen and just trigger
WARN_ON_ONCE() and fail the command with AC_ERR_SYSTEM.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Stefan Hübner <stefan.huebner@stud.tu-ilmenau.de>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>