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Subject[tip:core/smp] dcdbas: Make use of smp_call_on_cpu()
Commit-ID:  e23f22b5cb9e44da24cb8494707536211adff8d1
Gitweb: http://git.kernel.org/tip/e23f22b5cb9e44da24cb8494707536211adff8d1
Author: Juergen Gross <jgross@suse.com>
AuthorDate: Mon, 29 Aug 2016 08:48:46 +0200
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Mon, 5 Sep 2016 13:52:40 +0200

dcdbas: Make use of smp_call_on_cpu()

Use smp_call_on_cpu() to raise SMI on CPU 0.
Make call secure by adding get_online_cpus() to avoid e.g. suspend
resume cycles in between.

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Douglas_Warzecha@dell.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akataria@vmware.com
Cc: boris.ostrovsky@oracle.com
Cc: chrisw@sous-sol.org
Cc: david.vrabel@citrix.com
Cc: hpa@zytor.com
Cc: jdelvare@suse.com
Cc: jeremy@goop.org
Cc: linux@roeck-us.net
Cc: pali.rohar@gmail.com
Cc: rusty@rustcorp.com.au
Cc: virtualization@lists.linux-foundation.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1472453327-19050-6-git-send-email-jgross@suse.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
drivers/firmware/dcdbas.c | 51 ++++++++++++++++++++++++-----------------------
1 file changed, 26 insertions(+), 25 deletions(-)

diff --git a/drivers/firmware/dcdbas.c b/drivers/firmware/dcdbas.c
index 829eec8..2fe1a13 100644
--- a/drivers/firmware/dcdbas.c
+++ b/drivers/firmware/dcdbas.c
@@ -23,6 +23,7 @@
#include <linux/platform_device.h>
#include <linux/dma-mapping.h>
#include <linux/errno.h>
+#include <linux/cpu.h>
#include <linux/gfp.h>
#include <linux/init.h>
#include <linux/kernel.h>
@@ -238,33 +239,14 @@ static ssize_t host_control_on_shutdown_store(struct device *dev,
return count;
}

-/**
- * dcdbas_smi_request: generate SMI request
- *
- * Called with smi_data_lock.
- */
-int dcdbas_smi_request(struct smi_cmd *smi_cmd)
+static int raise_smi(void *par)
{
- cpumask_var_t old_mask;
- int ret = 0;
-
- if (smi_cmd->magic != SMI_CMD_MAGIC) {
- dev_info(&dcdbas_pdev->dev, "%s: invalid magic value\n",
- __func__);
- return -EBADR;
- }
+ struct smi_cmd *smi_cmd = par;

- /* SMI requires CPU 0 */
- if (!alloc_cpumask_var(&old_mask, GFP_KERNEL))
- return -ENOMEM;
-
- cpumask_copy(old_mask, &current->cpus_allowed);
- set_cpus_allowed_ptr(current, cpumask_of(0));
if (smp_processor_id() != 0) {
dev_dbg(&dcdbas_pdev->dev, "%s: failed to get CPU 0\n",
__func__);
- ret = -EBUSY;
- goto out;
+ return -EBUSY;
}

/* generate SMI */
@@ -280,9 +262,28 @@ int dcdbas_smi_request(struct smi_cmd *smi_cmd)
: "memory"
);

-out:
- set_cpus_allowed_ptr(current, old_mask);
- free_cpumask_var(old_mask);
+ return 0;
+}
+/**
+ * dcdbas_smi_request: generate SMI request
+ *
+ * Called with smi_data_lock.
+ */
+int dcdbas_smi_request(struct smi_cmd *smi_cmd)
+{
+ int ret;
+
+ if (smi_cmd->magic != SMI_CMD_MAGIC) {
+ dev_info(&dcdbas_pdev->dev, "%s: invalid magic value\n",
+ __func__);
+ return -EBADR;
+ }
+
+ /* SMI requires CPU 0 */
+ get_online_cpus();
+ ret = smp_call_on_cpu(0, raise_smi, smi_cmd, true);
+ put_online_cpus();
+
return ret;
}

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