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authorDavid Howells <dhowells@redhat.com>2006-10-05 14:55:46 +0100
committerDavid Howells <dhowells@warthog.cambridge.redhat.com>2006-10-05 15:10:12 +0100
commit7d12e780e003f93433d49ce78cfedf4b4c52adc5 (patch)
tree6748550400445c11a306b132009f3001e3525df8 /drivers/net/ibm_emac
parentda482792a6d1a3fbaaa25fae867b343fb4db3246 (diff)
downloadop-kernel-dev-7d12e780e003f93433d49ce78cfedf4b4c52adc5.zip
op-kernel-dev-7d12e780e003f93433d49ce78cfedf4b4c52adc5.tar.gz
IRQ: Maintain regs pointer globally rather than passing to IRQ handlers
Maintain a per-CPU global "struct pt_regs *" variable which can be used instead of passing regs around manually through all ~1800 interrupt handlers in the Linux kernel. The regs pointer is used in few places, but it potentially costs both stack space and code to pass it around. On the FRV arch, removing the regs parameter from all the genirq function results in a 20% speed up of the IRQ exit path (ie: from leaving timer_interrupt() to leaving do_IRQ()). Where appropriate, an arch may override the generic storage facility and do something different with the variable. On FRV, for instance, the address is maintained in GR28 at all times inside the kernel as part of general exception handling. Having looked over the code, it appears that the parameter may be handed down through up to twenty or so layers of functions. Consider a USB character device attached to a USB hub, attached to a USB controller that posts its interrupts through a cascaded auxiliary interrupt controller. A character device driver may want to pass regs to the sysrq handler through the input layer which adds another few layers of parameter passing. I've build this code with allyesconfig for x86_64 and i386. I've runtested the main part of the code on FRV and i386, though I can't test most of the drivers. I've also done partial conversion for powerpc and MIPS - these at least compile with minimal configurations. This will affect all archs. Mostly the changes should be relatively easy. Take do_IRQ(), store the regs pointer at the beginning, saving the old one: struct pt_regs *old_regs = set_irq_regs(regs); And put the old one back at the end: set_irq_regs(old_regs); Don't pass regs through to generic_handle_irq() or __do_IRQ(). In timer_interrupt(), this sort of change will be necessary: - update_process_times(user_mode(regs)); - profile_tick(CPU_PROFILING, regs); + update_process_times(user_mode(get_irq_regs())); + profile_tick(CPU_PROFILING); I'd like to move update_process_times()'s use of get_irq_regs() into itself, except that i386, alone of the archs, uses something other than user_mode(). Some notes on the interrupt handling in the drivers: (*) input_dev() is now gone entirely. The regs pointer is no longer stored in the input_dev struct. (*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking. It does something different depending on whether it's been supplied with a regs pointer or not. (*) Various IRQ handler function pointers have been moved to type irq_handler_t. Signed-Off-By: David Howells <dhowells@redhat.com> (cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)
Diffstat (limited to 'drivers/net/ibm_emac')
-rw-r--r--drivers/net/ibm_emac/ibm_emac_core.c4
-rw-r--r--drivers/net/ibm_emac/ibm_emac_debug.c3
-rw-r--r--drivers/net/ibm_emac/ibm_emac_mal.c10
3 files changed, 8 insertions, 9 deletions
diff --git a/drivers/net/ibm_emac/ibm_emac_core.c b/drivers/net/ibm_emac/ibm_emac_core.c
index d52e3bd..ffeafb2 100644
--- a/drivers/net/ibm_emac/ibm_emac_core.c
+++ b/drivers/net/ibm_emac/ibm_emac_core.c
@@ -184,7 +184,7 @@ static const char emac_stats_keys[EMAC_ETHTOOL_STATS_COUNT][ETH_GSTRING_LEN] = {
"tx_errors"
};
-static irqreturn_t emac_irq(int irq, void *dev_instance, struct pt_regs *regs);
+static irqreturn_t emac_irq(int irq, void *dev_instance);
static void emac_clean_tx_ring(struct ocp_enet_private *dev);
static inline int emac_phy_supports_gige(int phy_mode)
@@ -1515,7 +1515,7 @@ static void emac_rxde(void *param)
}
/* Hard IRQ */
-static irqreturn_t emac_irq(int irq, void *dev_instance, struct pt_regs *regs)
+static irqreturn_t emac_irq(int irq, void *dev_instance)
{
struct ocp_enet_private *dev = dev_instance;
struct emac_regs __iomem *p = dev->emacp;
diff --git a/drivers/net/ibm_emac/ibm_emac_debug.c b/drivers/net/ibm_emac/ibm_emac_debug.c
index c364590..92f970d 100644
--- a/drivers/net/ibm_emac/ibm_emac_debug.c
+++ b/drivers/net/ibm_emac/ibm_emac_debug.c
@@ -179,8 +179,7 @@ void emac_dbg_dump_all(void)
}
#if defined(CONFIG_MAGIC_SYSRQ)
-static void emac_sysrq_handler(int key, struct pt_regs *pt_regs,
- struct tty_struct *tty)
+static void emac_sysrq_handler(int key, struct tty_struct *tty)
{
emac_dbg_dump_all();
}
diff --git a/drivers/net/ibm_emac/ibm_emac_mal.c b/drivers/net/ibm_emac/ibm_emac_mal.c
index af50e7b..6c0f071 100644
--- a/drivers/net/ibm_emac/ibm_emac_mal.c
+++ b/drivers/net/ibm_emac/ibm_emac_mal.c
@@ -168,7 +168,7 @@ static inline void mal_disable_eob_irq(struct ibm_ocp_mal *mal)
MAL_DBG2("%d: disable_irq" NL, mal->def->index);
}
-static irqreturn_t mal_serr(int irq, void *dev_instance, struct pt_regs *regs)
+static irqreturn_t mal_serr(int irq, void *dev_instance)
{
struct ibm_ocp_mal *mal = dev_instance;
u32 esr = get_mal_dcrn(mal, MAL_ESR);
@@ -216,7 +216,7 @@ static inline void mal_schedule_poll(struct ibm_ocp_mal *mal)
MAL_DBG2("%d: already in poll" NL, mal->def->index);
}
-static irqreturn_t mal_txeob(int irq, void *dev_instance, struct pt_regs *regs)
+static irqreturn_t mal_txeob(int irq, void *dev_instance)
{
struct ibm_ocp_mal *mal = dev_instance;
u32 r = get_mal_dcrn(mal, MAL_TXEOBISR);
@@ -226,7 +226,7 @@ static irqreturn_t mal_txeob(int irq, void *dev_instance, struct pt_regs *regs)
return IRQ_HANDLED;
}
-static irqreturn_t mal_rxeob(int irq, void *dev_instance, struct pt_regs *regs)
+static irqreturn_t mal_rxeob(int irq, void *dev_instance)
{
struct ibm_ocp_mal *mal = dev_instance;
u32 r = get_mal_dcrn(mal, MAL_RXEOBISR);
@@ -236,7 +236,7 @@ static irqreturn_t mal_rxeob(int irq, void *dev_instance, struct pt_regs *regs)
return IRQ_HANDLED;
}
-static irqreturn_t mal_txde(int irq, void *dev_instance, struct pt_regs *regs)
+static irqreturn_t mal_txde(int irq, void *dev_instance)
{
struct ibm_ocp_mal *mal = dev_instance;
u32 deir = get_mal_dcrn(mal, MAL_TXDEIR);
@@ -252,7 +252,7 @@ static irqreturn_t mal_txde(int irq, void *dev_instance, struct pt_regs *regs)
return IRQ_HANDLED;
}
-static irqreturn_t mal_rxde(int irq, void *dev_instance, struct pt_regs *regs)
+static irqreturn_t mal_rxde(int irq, void *dev_instance)
{
struct ibm_ocp_mal *mal = dev_instance;
struct list_head *l;
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