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Subject[PATCH 14/18] 2.6.40: x86 idle floppy: remove deprecated disable_hlt()/enable_hlt()
Date
From: Len Brown <len.brown@intel.com>

The X86_32-only disable_hlt/enable_hlt mechanism was used
by the 32-bit floppy driver. Its effect was to replace
the use of the HLT instruction inside default_idle() with
cpu_relax().

This workaround was commented:
"disable hlt during certain critical i/o operations"

"This halt magic was a workaround for ancient floppy DMA
wreckage. It should be safe to remove."

Remove the workaround to simplify the idle loop.

cc: x86@kernel.org
Signed-off-by: Len Brown <len.brown@intel.com>
---
Documentation/feature-removal-schedule.txt | 8 ------
arch/x86/include/asm/system.h | 7 -----
arch/x86/kernel/process.c | 24 ------------------
drivers/block/floppy.c | 36 ----------------------------
4 files changed, 0 insertions(+), 75 deletions(-)
diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt
index 720e698..e1e9bf8 100644
--- a/Documentation/feature-removal-schedule.txt
+++ b/Documentation/feature-removal-schedule.txt
@@ -6,14 +6,6 @@ be removed from this file.

---------------------------

-What: x86 floppy disable_hlt
-When: 2.6.40
-Why: ancient workaround of dubious utility clutters the
- code used by everybody else.
-Who: Len Brown <len.brown@intel.com>
-
----------------------------
-
What: CONFIG_APM_CPU_IDLE, and its ability to call APM BIOS in idle
When: 2.6.40
Why: This optional sub-feature of APM is of dubious reliability,
diff --git a/arch/x86/include/asm/system.h b/arch/x86/include/asm/system.h
index 33ecc3e..013dd42 100644
--- a/arch/x86/include/asm/system.h
+++ b/arch/x86/include/asm/system.h
@@ -93,10 +93,6 @@ do { \
"memory"); \
} while (0)

-/*
- * disable hlt during certain critical i/o operations
- */
-#define HAVE_DISABLE_HLT
#else
#define __SAVE(reg, offset) "movq %%" #reg ",(14-" #offset ")*8(%%rsp)\n\t"
#define __RESTORE(reg, offset) "movq (14-" #offset ")*8(%%rsp),%%" #reg "\n\t"
@@ -337,9 +333,6 @@ static inline void clflush(volatile void *__p)

#define nop() asm volatile ("nop")

-void disable_hlt(void);
-void enable_hlt(void);
-
void cpu_idle_wait(void);

extern unsigned long arch_align_stack(unsigned long sp);
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index c485629..09bd118 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -344,34 +344,10 @@ void (*pm_idle)(void);
EXPORT_SYMBOL(pm_idle);
#endif

-#ifdef CONFIG_X86_32
-/*
- * This halt magic was a workaround for ancient floppy DMA
- * wreckage. It should be safe to remove.
- */
-static int hlt_counter;
-void disable_hlt(void)
-{
- hlt_counter++;
-}
-EXPORT_SYMBOL(disable_hlt);
-
-void enable_hlt(void)
-{
- hlt_counter--;
-}
-EXPORT_SYMBOL(enable_hlt);
-
-static inline int hlt_use_halt(void)
-{
- return !hlt_counter;
-}
-#else
static inline int hlt_use_halt(void)
{
return 1;
}
-#endif

/*
* We use this if we don't have any better
diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
index 41ea03f..9a4e006 100644
--- a/drivers/block/floppy.c
+++ b/drivers/block/floppy.c
@@ -1032,37 +1032,6 @@ static int fd_wait_for_completion(unsigned long delay, timeout_fn function)
return 0;
}

-static DEFINE_SPINLOCK(floppy_hlt_lock);
-static int hlt_disabled;
-static void floppy_disable_hlt(void)
-{
- unsigned long flags;
-
- WARN_ONCE(1, "floppy_disable_hlt() scheduled for removal in 2.6.40");
- spin_lock_irqsave(&floppy_hlt_lock, flags);
- if (!hlt_disabled) {
- hlt_disabled = 1;
-#ifdef HAVE_DISABLE_HLT
- disable_hlt();
-#endif
- }
- spin_unlock_irqrestore(&floppy_hlt_lock, flags);
-}
-
-static void floppy_enable_hlt(void)
-{
- unsigned long flags;
-
- spin_lock_irqsave(&floppy_hlt_lock, flags);
- if (hlt_disabled) {
- hlt_disabled = 0;
-#ifdef HAVE_DISABLE_HLT
- enable_hlt();
-#endif
- }
- spin_unlock_irqrestore(&floppy_hlt_lock, flags);
-}
-
static void setup_DMA(void)
{
unsigned long f;
@@ -1107,7 +1076,6 @@ static void setup_DMA(void)
fd_enable_dma();
release_dma_lock(f);
#endif
- floppy_disable_hlt();
}

static void show_floppy(void);
@@ -1709,7 +1677,6 @@ irqreturn_t floppy_interrupt(int irq, void *dev_id)
fd_disable_dma();
release_dma_lock(f);

- floppy_enable_hlt();
do_floppy = NULL;
if (fdc >= N_FDC || FDCS->address == -1) {
/* we don't even know which FDC is the culprit */
@@ -1858,8 +1825,6 @@ static void floppy_shutdown(unsigned long data)
show_floppy();
cancel_activity();

- floppy_enable_hlt();
-
flags = claim_dma_lock();
fd_disable_dma();
release_dma_lock(flags);
@@ -4504,7 +4469,6 @@ static void floppy_release_irq_and_dma(void)
#if N_FDC > 1
set_dor(1, ~8, 0);
#endif
- floppy_enable_hlt();

if (floppy_track_buffer && max_buffer_sectors) {
tmpsize = max_buffer_sectors * 1024;
--
1.7.5.rc0


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