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Subject[PATCH 4.8 083/125] s390/cio: fix accidental interrupt enabling during resume
Date
4.8-stable review patch.  If anyone has any objections, please let me know.

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

From: Sebastian Ott <sebott@linux.vnet.ibm.com>

commit d53c51f26145657aa7c55fa396f93677e613548d upstream.

Since commit 9f3d6d7 chsc_get_channel_measurement_chars is called with
interrupts disabled during resume from hibernate. Since this function
used spin_unlock_irq, interrupts have been enabled accidentally. Fix
this by using the irqsave variant.

Since we can't guarantee the IRQ-enablement state for all (future/
external) callers, change the locking in related functions to prevent
similar bugs in the future.

Fixes: 9f3d6d7 ("s390/cio: update measurement characteristics")
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/s390/cio/chsc.c | 20 ++++++++++++--------
1 file changed, 12 insertions(+), 8 deletions(-)

--- a/drivers/s390/cio/chsc.c
+++ b/drivers/s390/cio/chsc.c
@@ -95,12 +95,13 @@ struct chsc_ssd_area {
int chsc_get_ssd_info(struct subchannel_id schid, struct chsc_ssd_info *ssd)
{
struct chsc_ssd_area *ssd_area;
+ unsigned long flags;
int ccode;
int ret;
int i;
int mask;

- spin_lock_irq(&chsc_page_lock);
+ spin_lock_irqsave(&chsc_page_lock, flags);
memset(chsc_page, 0, PAGE_SIZE);
ssd_area = chsc_page;
ssd_area->request.length = 0x0010;
@@ -144,7 +145,7 @@ int chsc_get_ssd_info(struct subchannel_
ssd->fla[i] = ssd_area->fla[i];
}
out:
- spin_unlock_irq(&chsc_page_lock);
+ spin_unlock_irqrestore(&chsc_page_lock, flags);
return ret;
}

@@ -832,9 +833,10 @@ int __chsc_do_secm(struct channel_subsys
u32 fmt : 4;
u32 : 16;
} __attribute__ ((packed)) *secm_area;
+ unsigned long flags;
int ret, ccode;

- spin_lock_irq(&chsc_page_lock);
+ spin_lock_irqsave(&chsc_page_lock, flags);
memset(chsc_page, 0, PAGE_SIZE);
secm_area = chsc_page;
secm_area->request.length = 0x0050;
@@ -864,7 +866,7 @@ int __chsc_do_secm(struct channel_subsys
CIO_CRW_EVENT(2, "chsc: secm failed (rc=%04x)\n",
secm_area->response.code);
out:
- spin_unlock_irq(&chsc_page_lock);
+ spin_unlock_irqrestore(&chsc_page_lock, flags);
return ret;
}

@@ -992,6 +994,7 @@ chsc_initialize_cmg_chars(struct channel

int chsc_get_channel_measurement_chars(struct channel_path *chp)
{
+ unsigned long flags;
int ccode, ret;

struct {
@@ -1021,7 +1024,7 @@ int chsc_get_channel_measurement_chars(s
if (!css_chsc_characteristics.scmc || !css_chsc_characteristics.secm)
return -EINVAL;

- spin_lock_irq(&chsc_page_lock);
+ spin_lock_irqsave(&chsc_page_lock, flags);
memset(chsc_page, 0, PAGE_SIZE);
scmc_area = chsc_page;
scmc_area->request.length = 0x0010;
@@ -1053,7 +1056,7 @@ int chsc_get_channel_measurement_chars(s
chsc_initialize_cmg_chars(chp, scmc_area->cmcv,
(struct cmg_chars *) &scmc_area->data);
out:
- spin_unlock_irq(&chsc_page_lock);
+ spin_unlock_irqrestore(&chsc_page_lock, flags);
return ret;
}

@@ -1134,6 +1137,7 @@ struct css_chsc_char css_chsc_characteri
int __init
chsc_determine_css_characteristics(void)
{
+ unsigned long flags;
int result;
struct {
struct chsc_header request;
@@ -1146,7 +1150,7 @@ chsc_determine_css_characteristics(void)
u32 chsc_char[508];
} __attribute__ ((packed)) *scsc_area;

- spin_lock_irq(&chsc_page_lock);
+ spin_lock_irqsave(&chsc_page_lock, flags);
memset(chsc_page, 0, PAGE_SIZE);
scsc_area = chsc_page;
scsc_area->request.length = 0x0010;
@@ -1168,7 +1172,7 @@ chsc_determine_css_characteristics(void)
CIO_CRW_EVENT(2, "chsc: scsc failed (rc=%04x)\n",
scsc_area->response.code);
exit:
- spin_unlock_irq(&chsc_page_lock);
+ spin_unlock_irqrestore(&chsc_page_lock, flags);
return result;
}


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