Re: [PATCH 1/1] work_on_cpu: use in drivers/pci/pci-driver.c

From: Rusty Russell
Date: Wed Dec 31 2008 - 08:25:28 EST


On Wednesday 10 December 2008 09:22:48 Jesse Barnes wrote:
> On Monday, December 01, 2008 12:20 am Rusty Russell wrote:
> > This uses work_on_cpu(), rather than altering the cpumask of the
> > thread which we happen to be.
>
> Nice, I applied this to my linux-next branch to get some build/test coverage.
> Please cc linux-pci in the future though.

Hi Jesse,

I don't see this in linux-next, nor Linus' tree. Here it is again...

Subject: work_on_cpu: use in drivers/pci/pci-driver.c

This uses work_on_cpu(), rather than altering the cpumask of the
thread which we happen to be.

Note the cleanups:

1) I've removed the CONFIG_NUMA test, since dev_to_node() returns -1
for !CONFIG_NUMA anyway and the compiler will eliminate it.

2) No need to reset mempolicy to default (a bad idea anyway) since
work_on_cpu is run from a workqueue.

Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: Jesse Barnes <jbarnes@xxxxxxxxxxxxxxxx>
---
drivers/pci/pci-driver.c | 52 ++++++++++++++++++++++++++++-------------------
1 file changed, 32 insertions(+), 20 deletions(-)

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -16,6 +16,7 @@
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/sched.h>
+#include <linux/cpu.h>
#include "pci.h"

/*
@@ -183,32 +184,43 @@ static const struct pci_device_id *pci_m
return pci_match_id(drv->id_table, dev);
}

+struct drv_dev_and_id {
+ struct pci_driver *drv;
+ struct pci_dev *dev;
+ const struct pci_device_id *id;
+};
+
+static long local_pci_probe(void *_ddi)
+{
+ struct drv_dev_and_id *ddi = _ddi;
+
+ return ddi->drv->probe(ddi->dev, ddi->id);
+}
+
static int pci_call_probe(struct pci_driver *drv, struct pci_dev *dev,
const struct pci_device_id *id)
{
- int error;
-#ifdef CONFIG_NUMA
- /* Execute driver initialization on node where the
- device's bus is attached to. This way the driver likely
- allocates its local memory on the right node without
- any need to change it. */
- struct mempolicy *oldpol;
- cpumask_t oldmask = current->cpus_allowed;
- int node = dev_to_node(&dev->dev);
+ int error, node;
+ struct drv_dev_and_id ddi = { drv, dev, id };

+ /* Execute driver initialization on node where the device's
+ bus is attached to. This way the driver likely allocates
+ its local memory on the right node without any need to
+ change it. */
+ node = dev_to_node(&dev->dev);
if (node >= 0) {
+ int cpu;
node_to_cpumask_ptr(nodecpumask, node);
- set_cpus_allowed_ptr(current, nodecpumask);
- }
- /* And set default memory allocation policy */
- oldpol = current->mempolicy;
- current->mempolicy = NULL; /* fall back to system default policy */
-#endif
- error = drv->probe(dev, id);
-#ifdef CONFIG_NUMA
- set_cpus_allowed_ptr(current, &oldmask);
- current->mempolicy = oldpol;
-#endif
+
+ get_online_cpus();
+ cpu = cpumask_any_and(nodecpumask, cpu_online_mask);
+ if (cpu < nr_cpu_ids)
+ error = work_on_cpu(cpu, local_pci_probe, &ddi);
+ else
+ error = local_pci_probe(&ddi);
+ put_online_cpus();
+ } else
+ error = local_pci_probe(&ddi);
return error;
}


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