The .alloc_pdata scheduler hook must, before this change,
be implemented by all schedulers --even those ones that
don't need to allocate anything.
Make it possible to just use the SCHED_OP(), like for
the other hooks, by using ERR_PTR() and IS_ERR() for
error reporting. This:
- makes NULL a variant of success;
- allows for errors other than ENOMEM to be properly
communicated (if ever necessary).
This, in turn, means that schedulers not needing to
allocate any per-pCPU data, can avoid implementing the
hook. In fact, the artificial implementation of
.alloc_pdata in the ARINC653 is removed (and, while there,
nuke .free_pdata too, as it is equally useless).
Signed-off-by: Dario Faggioli <dario.faggi...@citrix.com>
Reviewed-by: Meng Xu <men...@cis.upenn.edu>
Reviewed-by: Juergen Gross <jgr...@suse.com>
Acked-by: George Dunlap <george.dun...@eu.citrix.com>
---
Cc: Robert VanVossen <robert.vanvos...@dornerworks.com>
Cc: Josh Whitehead <josh.whiteh...@dornerworks.com>
Cc: Jan Beulich <jbeul...@suse.com>
---
Changes from v1:
* only update sd->sched_priv if alloc_pdata does not return
IS_ERR, so that xfree() can always be safely called on
sd->sched_priv itself, as requested during review;
* xen/err.h included in .c files that actually need it,
instead than in sched-if.h.
---
xen/common/sched_arinc653.c | 31 -------------------------------
xen/common/sched_credit.c | 5 +++--
xen/common/sched_credit2.c | 2 +-
xen/common/sched_rt.c | 8 ++++----
xen/common/schedule.c | 27 +++++++++++++++++----------
5 files changed, 25 insertions(+), 48 deletions(-)
diff --git a/xen/common/sched_arinc653.c b/xen/common/sched_arinc653.c
index 8a11a2f..b79fcdf 100644
--- a/xen/common/sched_arinc653.c
+++ b/xen/common/sched_arinc653.c
@@ -456,34 +456,6 @@ a653sched_free_vdata(const struct scheduler *ops, void
*priv)
}
/**
- * This function allocates scheduler-specific data for a physical CPU
- *
- * We do not actually make use of any per-CPU data but the hypervisor expects
- * a non-NULL return value
- *
- * @param ops Pointer to this instance of the scheduler structure
- *
- * @return Pointer to the allocated data
- */
-static void *
-a653sched_alloc_pdata(const struct scheduler *ops, int cpu)
-{
- /* return a non-NULL value to keep schedule.c happy */
- return SCHED_PRIV(ops);
-}
-
-/**
- * This function frees scheduler-specific data for a physical CPU
- *
- * @param ops Pointer to this instance of the scheduler structure
- */
-static void
-a653sched_free_pdata(const struct scheduler *ops, void *pcpu, int cpu)
-{
- /* nop */
-}
-
-/**
* This function allocates scheduler-specific data for a domain
*
* We do not actually make use of any per-domain data but the hypervisor
@@ -737,9 +709,6 @@ static const struct scheduler sched_arinc653_def = {
.free_vdata = a653sched_free_vdata,
.alloc_vdata = a653sched_alloc_vdata,
- .free_pdata = a653sched_free_pdata,
- .alloc_pdata = a653sched_alloc_pdata,
-
.free_domdata = a653sched_free_domdata,
.alloc_domdata = a653sched_alloc_domdata,
diff --git a/xen/common/sched_credit.c b/xen/common/sched_credit.c
index 4c4927f..63a4a63 100644
--- a/xen/common/sched_credit.c
+++ b/xen/common/sched_credit.c
@@ -23,6 +23,7 @@
#include <xen/errno.h>
#include <xen/keyhandler.h>
#include <xen/trace.h>
+#include <xen/err.h>
/*
@@ -532,12 +533,12 @@ csched_alloc_pdata(const struct scheduler *ops, int cpu)
/* Allocate per-PCPU info */
spc = xzalloc(struct csched_pcpu);
if ( spc == NULL )
- return NULL;
+ return ERR_PTR(-ENOMEM);
if ( !alloc_cpumask_var(&spc->balance_mask) )
{
xfree(spc);
- return NULL;
+ return ERR_PTR(-ENOMEM);
}
spin_lock_irqsave(&prv->lock, flags);
diff --git a/xen/common/sched_credit2.c b/xen/common/sched_credit2.c
index b8c8e40..e97d8be 100644
--- a/xen/common/sched_credit2.c
+++ b/xen/common/sched_credit2.c
@@ -2047,7 +2047,7 @@ csched2_alloc_pdata(const struct scheduler *ops, int cpu)
printk("%s: cpu %d not online yet, deferring initializatgion\n",
__func__, cpu);
- return (void *)1;
+ return NULL;
}
static void
diff --git a/xen/common/sched_rt.c b/xen/common/sched_rt.c
index 321b0a5..aece318 100644
--- a/xen/common/sched_rt.c
+++ b/xen/common/sched_rt.c
@@ -29,6 +29,7 @@
#include <xen/cpu.h>
#include <xen/keyhandler.h>
#include <xen/trace.h>
+#include <xen/err.h>
#include <xen/guest_access.h>
/*
@@ -681,7 +682,7 @@ rt_alloc_pdata(const struct scheduler *ops, int cpu)
spin_unlock_irqrestore(old_lock, flags);
if ( !alloc_cpumask_var(&_cpumask_scratch[cpu]) )
- return NULL;
+ return ERR_PTR(-ENOMEM);
if ( prv->repl_timer == NULL )
{
@@ -689,13 +690,12 @@ rt_alloc_pdata(const struct scheduler *ops, int cpu)
prv->repl_timer = xzalloc(struct timer);
if ( prv->repl_timer == NULL )
- return NULL;
+ return ERR_PTR(-ENOMEM);
init_timer(prv->repl_timer, repl_timer_handler, (void *)ops, cpu);
}
- /* 1 indicates alloc. succeed in schedule.c */
- return (void *)1;
+ return NULL;
}
static void
diff --git a/xen/common/schedule.c b/xen/common/schedule.c
index b7dee16..1941613 100644
--- a/xen/common/schedule.c
+++ b/xen/common/schedule.c
@@ -37,6 +37,7 @@
#include <xen/event.h>
#include <public/sched.h>
#include <xsm/xsm.h>
+#include <xen/err.h>
/* opt_sched: scheduler - default to configured value */
static char __initdata opt_sched[10] = CONFIG_SCHED_DEFAULT;
@@ -1462,6 +1463,7 @@ static void poll_timer_fn(void *data)
static int cpu_schedule_up(unsigned int cpu)
{
struct schedule_data *sd = &per_cpu(schedule_data, cpu);
+ void *sched_priv;
per_cpu(scheduler, cpu) = &ops;
spin_lock_init(&sd->_lock);
@@ -1500,9 +1502,16 @@ static int cpu_schedule_up(unsigned int cpu)
if ( idle_vcpu[cpu] == NULL )
return -ENOMEM;
- if ( (ops.alloc_pdata != NULL) &&
- ((sd->sched_priv = ops.alloc_pdata(&ops, cpu)) == NULL) )
- return -ENOMEM;
+ /*
+ * We don't want to risk calling xfree() on an sd->sched_priv
+ * (e.g., inside free_pdata, from cpu_schedule_down() called
+ * during CPU_UP_CANCELLED) that contains an IS_ERR value.
+ */
+ sched_priv = SCHED_OP(&ops, alloc_pdata, cpu);
+ if ( IS_ERR(sched_priv) )
+ return PTR_ERR(sched_priv);
+
+ sd->sched_priv = sched_priv;
return 0;
}
@@ -1512,8 +1521,7 @@ static void cpu_schedule_down(unsigned int cpu)
struct schedule_data *sd = &per_cpu(schedule_data, cpu);
struct scheduler *sched = per_cpu(scheduler, cpu);
- if ( sd->sched_priv != NULL )
- SCHED_OP(sched, free_pdata, sd->sched_priv, cpu);
+ SCHED_OP(sched, free_pdata, sd->sched_priv, cpu);
SCHED_OP(sched, free_vdata, idle_vcpu[cpu]->sched_priv);
idle_vcpu[cpu]->sched_priv = NULL;
@@ -1608,9 +1616,8 @@ void __init scheduler_init(void)
idle_domain->max_vcpus = nr_cpu_ids;
if ( alloc_vcpu(idle_domain, 0, 0) == NULL )
BUG();
- if ( ops.alloc_pdata &&
- !(this_cpu(schedule_data).sched_priv = ops.alloc_pdata(&ops, 0)) )
- BUG();
+ this_cpu(schedule_data).sched_priv = SCHED_OP(&ops, alloc_pdata, 0);
+ BUG_ON(IS_ERR(this_cpu(schedule_data).sched_priv));
SCHED_OP(&ops, init_pdata, this_cpu(schedule_data).sched_priv, 0);
}
@@ -1653,8 +1660,8 @@ int schedule_cpu_switch(unsigned int cpu, struct cpupool
*c)
idle = idle_vcpu[cpu];
ppriv = SCHED_OP(new_ops, alloc_pdata, cpu);
- if ( ppriv == NULL )
- return -ENOMEM;
+ if ( IS_ERR(ppriv) )
+ return PTR_ERR(ppriv);
SCHED_OP(new_ops, init_pdata, ppriv, cpu);
vpriv = SCHED_OP(new_ops, alloc_vdata, idle, idle->domain->sched_priv);
if ( vpriv == NULL )
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