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Subject[PATCH v2] sparse: use force attribute for vm_fault_t casts
Fixes sparse warnings:
./include/trace/events/fs_dax.h:10:1: sparse:
got restricted vm_fault_t
./include/trace/events/fs_dax.h:153:1: sparse:
got restricted vm_fault_t
fs/dax.c:563:39: sparse: got restricted vm_fault_t
fs/dax.c:565:39: sparse: got restricted vm_fault_t
fs/dax.c:569:31: sparse: got restricted vm_fault_t
fs/dax.c:1055:41: sparse:
got restricted vm_fault_t [assigned] [usertype] ret
fs/dax.c:1461:46: sparse: got restricted vm_fault_t [usertype] ret
fs/dax.c:1477:21: sparse:
expected restricted vm_fault_t [assigned] [usertype] ret
fs/dax.c:1518:51: sparse:
got restricted vm_fault_t [assigned] [usertype] ret
fs/dax.c:1599:21: sparse:
expected restricted vm_fault_t [assigned] [usertype] ret
fs/dax.c:1633:62: sparse:
got restricted vm_fault_t [assigned] [usertype] ret
fs/dax.c:1696:55: sparse: got restricted vm_fault_t
fs/dax.c:1711:58: sparse:
got restricted vm_fault_t [assigned] [usertype] ret

vm_fault_t type is bitwise and requires __force attribute for any casts.

Signed-off-by: Vasily Averin <vvs@openvz.org>
---
v2: improved according to the recommendations of Matthew Wilcox:
- __force cast moved into internal functions
- introduced new abstractions dax_vm_fault_[en|de]code()
---
fs/dax.c | 21 +++++++++++++++------
include/linux/mm_types.h | 30 ++++++++++++++++--------------
include/trace/events/fs_dax.h | 12 ++++++------
3 files changed, 37 insertions(+), 26 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index 67a08a32fccb..c27c8782007f 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -121,6 +121,15 @@ static int dax_is_empty_entry(void *entry)
return xa_to_value(entry) & DAX_EMPTY;
}

+static void *dax_vm_fault_encode(vm_fault_t fault)
+{
+ return xa_mk_internal((__force unsigned long)fault);
+}
+
+static vm_fault_t dax_vm_fault_decode(void *entry)
+{
+ return (__force vm_fault_t)xa_to_internal(entry);
+}
/*
* true if the entry that was found is of a smaller order than the entry
* we were looking for
@@ -560,13 +569,13 @@ static void *grab_mapping_entry(struct xa_state *xas,
if (xas_nomem(xas, mapping_gfp_mask(mapping) & ~__GFP_HIGHMEM))
goto retry;
if (xas->xa_node == XA_ERROR(-ENOMEM))
- return xa_mk_internal(VM_FAULT_OOM);
+ return dax_vm_fault_encode(VM_FAULT_OOM);
if (xas_error(xas))
- return xa_mk_internal(VM_FAULT_SIGBUS);
+ return dax_vm_fault_encode(VM_FAULT_SIGBUS);
return entry;
fallback:
xas_unlock_irq(xas);
- return xa_mk_internal(VM_FAULT_FALLBACK);
+ return dax_vm_fault_encode(VM_FAULT_FALLBACK);
}

/**
@@ -1474,7 +1483,7 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,

entry = grab_mapping_entry(&xas, mapping, 0);
if (xa_is_internal(entry)) {
- ret = xa_to_internal(entry);
+ ret = dax_vm_fault_decode(entry);
goto out;
}

@@ -1578,7 +1587,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
*/
max_pgoff = DIV_ROUND_UP(i_size_read(iter.inode), PAGE_SIZE);

- trace_dax_pmd_fault(iter.inode, vmf, max_pgoff, 0);
+ trace_dax_pmd_fault(iter.inode, vmf, max_pgoff, (vm_fault_t)0);

if (xas.xa_index >= max_pgoff) {
ret = VM_FAULT_SIGBUS;
@@ -1596,7 +1605,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
*/
entry = grab_mapping_entry(&xas, mapping, PMD_ORDER);
if (xa_is_internal(entry)) {
- ret = xa_to_internal(entry);
+ ret = dax_vm_fault_decode(entry);
goto fallback;
}

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 8834e38c06a4..57cc4918b1b1 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -745,20 +745,22 @@ enum vm_fault_reason {
VM_FAULT_SIGSEGV | VM_FAULT_HWPOISON | \
VM_FAULT_HWPOISON_LARGE | VM_FAULT_FALLBACK)

-#define VM_FAULT_RESULT_TRACE \
- { VM_FAULT_OOM, "OOM" }, \
- { VM_FAULT_SIGBUS, "SIGBUS" }, \
- { VM_FAULT_MAJOR, "MAJOR" }, \
- { VM_FAULT_WRITE, "WRITE" }, \
- { VM_FAULT_HWPOISON, "HWPOISON" }, \
- { VM_FAULT_HWPOISON_LARGE, "HWPOISON_LARGE" }, \
- { VM_FAULT_SIGSEGV, "SIGSEGV" }, \
- { VM_FAULT_NOPAGE, "NOPAGE" }, \
- { VM_FAULT_LOCKED, "LOCKED" }, \
- { VM_FAULT_RETRY, "RETRY" }, \
- { VM_FAULT_FALLBACK, "FALLBACK" }, \
- { VM_FAULT_DONE_COW, "DONE_COW" }, \
- { VM_FAULT_NEEDDSYNC, "NEEDDSYNC" }
+#define faultflag_string(flag) {(__force unsigned long)VM_FAULT_##flag, #flag}
+
+#define VM_FAULT_RESULT_TRACE \
+ faultflag_string(OOM), \
+ faultflag_string(SIGBUS), \
+ faultflag_string(MAJOR), \
+ faultflag_string(WRITE), \
+ faultflag_string(HWPOISON), \
+ faultflag_string(HWPOISON_LARGE), \
+ faultflag_string(SIGSEGV), \
+ faultflag_string(NOPAGE), \
+ faultflag_string(LOCKED), \
+ faultflag_string(RETRY), \
+ faultflag_string(FALLBACK), \
+ faultflag_string(DONE_COW), \
+ faultflag_string(NEEDDSYNC)

struct vm_special_mapping {
const char *name; /* The name, e.g. "[vdso]". */
diff --git a/include/trace/events/fs_dax.h b/include/trace/events/fs_dax.h
index 97b09fcf7e52..75908bdc7b2d 100644
--- a/include/trace/events/fs_dax.h
+++ b/include/trace/events/fs_dax.h
@@ -9,7 +9,7 @@

DECLARE_EVENT_CLASS(dax_pmd_fault_class,
TP_PROTO(struct inode *inode, struct vm_fault *vmf,
- pgoff_t max_pgoff, int result),
+ pgoff_t max_pgoff, vm_fault_t result),
TP_ARGS(inode, vmf, max_pgoff, result),
TP_STRUCT__entry(
__field(unsigned long, ino)
@@ -33,7 +33,7 @@ DECLARE_EVENT_CLASS(dax_pmd_fault_class,
__entry->flags = vmf->flags;
__entry->pgoff = vmf->pgoff;
__entry->max_pgoff = max_pgoff;
- __entry->result = result;
+ __entry->result = (__force int)result;
),
TP_printk("dev %d:%d ino %#lx %s %s address %#lx vm_start "
"%#lx vm_end %#lx pgoff %#lx max_pgoff %#lx %s",
@@ -54,7 +54,7 @@ DECLARE_EVENT_CLASS(dax_pmd_fault_class,
#define DEFINE_PMD_FAULT_EVENT(name) \
DEFINE_EVENT(dax_pmd_fault_class, name, \
TP_PROTO(struct inode *inode, struct vm_fault *vmf, \
- pgoff_t max_pgoff, int result), \
+ pgoff_t max_pgoff, vm_fault_t result), \
TP_ARGS(inode, vmf, max_pgoff, result))

DEFINE_PMD_FAULT_EVENT(dax_pmd_fault);
@@ -151,7 +151,7 @@ DEFINE_EVENT(dax_pmd_insert_mapping_class, name, \
DEFINE_PMD_INSERT_MAPPING_EVENT(dax_pmd_insert_mapping);

DECLARE_EVENT_CLASS(dax_pte_fault_class,
- TP_PROTO(struct inode *inode, struct vm_fault *vmf, int result),
+ TP_PROTO(struct inode *inode, struct vm_fault *vmf, vm_fault_t result),
TP_ARGS(inode, vmf, result),
TP_STRUCT__entry(
__field(unsigned long, ino)
@@ -169,7 +169,7 @@ DECLARE_EVENT_CLASS(dax_pte_fault_class,
__entry->address = vmf->address;
__entry->flags = vmf->flags;
__entry->pgoff = vmf->pgoff;
- __entry->result = result;
+ __entry->result = (__force int)result;
),
TP_printk("dev %d:%d ino %#lx %s %s address %#lx pgoff %#lx %s",
MAJOR(__entry->dev),
@@ -185,7 +185,7 @@ DECLARE_EVENT_CLASS(dax_pte_fault_class,

#define DEFINE_PTE_FAULT_EVENT(name) \
DEFINE_EVENT(dax_pte_fault_class, name, \
- TP_PROTO(struct inode *inode, struct vm_fault *vmf, int result), \
+ TP_PROTO(struct inode *inode, struct vm_fault *vmf, vm_fault_t result), \
TP_ARGS(inode, vmf, result))

DEFINE_PTE_FAULT_EVENT(dax_pte_fault);
--
2.31.1
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