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  1. 21 4月, 2014 1 次提交
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      ACPICA: Tables: Clean up split INSTALLED/VALIDATED table state logics. · 7f9fc99c
      由 Lv Zheng 提交于 
      This patch is mainly a naming cleanup to clarify hidden logics, no
functional changes.

acpi_initialize_tables() is used by Linux to install table addresses for
early boot steps.  During this stage, table addresses are mapped by
early_ioremap() mechanism which is different from the runtime IO mappings.
Thus it is not safe for ACPICA to keep mapped pointers in struct acpi_table_desc
structure during this stage.

In order to support this in ACPICA, table states are divided into
1. "INSTALLED" (where struct acpi_table_desc.Pointer is always NULL) and
2. "VALIDATED" (where struct acpi_table_desc.Pointer is always not NULL).
During acpi_initialize_tables(), table state are ensured to be "INSTALLED"
but not "VALIDATED".  This logic is ensured by the original code in very
ambigious way.  For example, currently acpi_tb_delete_table() is invoked in
some place to perform an uninstallation while it is invoked in other place
to perform an invalidation.  They happen to work just because no one enters
the penalty where the 2 behaviours are not equivalent.

The naming cleanups are made in this patch:
A. For installation and validation:
   There is code setting struct acpi_table_desc.Pointer first and delete it
   immediately to keep the descriptor's state as "INSTALLED" during the
   installation.  This patch implements this in more direct way.  After
   applying it, struct acpi_table_desc.Pointer will never be set in
   acpi_tb_install_table() and acpi_tb_override_table() as they are the only
   functions invoked during acpi_initialize_tables(). This is achieved by:
1. Rename acpi_tb_verify_table() to acpi_tb_validate_table() to clarify this
   change.
2. Rename acpi_tb_table_override() to acpi_tb_override_table() to keep nameing
   consistencies as other APIs (verb. Table).
3. Stops setting struct acpi_table_desc.Pointer in acpi_tb_install_table() and
   acpi_tb_table_override().
4. Introduce acpi_tb_acquire_table() to acquire the table pointer that is not
   maintained in the struct acpi_table_desc of the global root table list and
   rewrite acpi_tb_validate_table() using this new function to reduce
   redundancies.
5. Replace the table pointer using the overridden table pointer in
   acpi_tb_add_table(). As acpi_tb_add_table() is not invoked during early boot
   stage, tables returned from this functions should be "VALIDATED".  As
   acpi_tb_override_table() is modified by this patch to return a "INSTALLED"
   but not "VALIDATED" descriptor, to keep acpi_tb_add_table() unchanged,
   struct acpi_table_desc.Pointer is filled in acpi_tb_add_table().
B. For invalidation and uninstallation:
   The original code invalidate table by invoking acpi_tb_delete_table() here
   and there, but actually this function should only be used to uninstall
   tables.  This can work just because its invocations are equivalent to
   invalidation in some cases.
   This patch splits acpi_tb_delete_table() into acpi_tb_invalidate_table() and
   acpi_tb_uninstall_table() and cleans up the hidden logic using the new
   APIs.  This is achieved by:
1. Rename acpi_tb_delete_table() to acpi_tb_uninstall_table() as it is mainly
   called before resetting struct acpi_table_desc.Address.  Thus the table
   descriptor is in "not INSTALLED" state.  This patch enforces this by
   setting struct acpi_table_desc.Address to NULL in this function.
2. Introduce acpi_tb_invalidate_table() to be the reversal of
   acpi_tb_validate_table() and invoke it in acpi_tb_uninstall_table().
3. Introduce acpi_tb_release_table() to release the table pointer that is not
   maintained in acpi_gbl_root_table_list and rewrite acpi_tb_invalidate_table()
   using this new function to reduce redundancies.

After cleaning up, the maintainability of the internal APIs are also
improved:
1. acpi_tb_acquire_table: Acquire struct acpi_table_header according to
                       ACPI_TABLE_ORIGIN_xxx flags.
2. acpi_tb_release_table: Release struct acpi_table_header according to
                       ACPI_TABLE_ORIGIN_xxx flags.
3. acpi_tb_install_table: Make struct acpi_table_desc.Address not NULL according to
                       ACPI_TABLE_ORIGIN_xxx flags.
4. acpi_tb_uninstall_table: Make struct acpi_table_desc.Address NULL according to
                         ACPI_TABLE_ORIGIN_xxx flags.
5. acpi_tb_validate_table: Make struct acpi_table_desc.Pointer not NULL according to
                        ACPI_TABLE_ORIGIN_xxx flags.
6. acpi_tb_invalidate_table: Make struct acpi_table_desc.Pointer NULL according to
                          ACPI_TABLE_ORIGIN_xxx flags.
7. acpi_tb_override_table: Replace struct acpi_table_desc.Address and
                        struct acpi_table_desc.Flags.  It only happens in
                        "INSTALLED" state.

The patch has been unit tested in acpi_exec by:
1. Initializing;
2. Executing exc_tbl ASLTS tests;
3. Executing "Load" command.
So that all original acpi_tb_install_table() and acpi_tb_override_table()
invocations are covered.

Known Issues:
1. Cleanup acpi_tb_add_table() to Kill Code Redundancies
   Current implementation in acpi_tb_add_table() is not very clean, further
   patch can rewrite acpi_tb_add_table() with ordered acpi_tb_install_table(),
   acpi_tb_override_table() and acpi_tb_validate_table(). It is not done in this
   patch so that it is easy for the reviewers to understand the changes in
   this patch.
Signed-off-by: NLv Zheng <lv.zheng@intel.com>
Signed-off-by: NBob Moore <robert.moore@intel.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      7f9fc99c
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