From: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
commit d5a9bf0b38d2ac85c9a693c7fb851f74fd2a2494 upstream.
I have here a FPGA behind PCIe which exports SRAM which I use for
pstore. Now it seems that the FPGA no longer supports cmpxchg based
updates and writes back 0xffâ?¦ff and returns the same. This leads to
crash during crash rendering pstore useless.
Since I doubt that there is much benefit from using cmpxchg() here, I am
dropping this atomic access and use the spinlock based version.
Cc: Anton Vorontsov <anton@xxxxxxxxxx>
Cc: Colin Cross <ccross@xxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Cc: Rabin Vincent <rabinv@xxxxxxxx>
Tested-by: Rabin Vincent <rabinv@xxxxxxxx>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>
[kees: remove "_locked" suffix since it's the only option now]
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Willy Tarreau <w@xxxxxx>
---
fs/pstore/ram_core.c | 43 ++-----------------------------------------
1 file changed, 2 insertions(+), 41 deletions(-)
diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c
index 0b367ef..ee3c6ec 100644
--- a/fs/pstore/ram_core.c
+++ b/fs/pstore/ram_core.c
@@ -45,43 +45,10 @@ static inline size_t buffer_start(struct persistent_ram_zone *prz)
return atomic_read(&prz->buffer->start);
}
-/* increase and wrap the start pointer, returning the old value */
-static size_t buffer_start_add_atomic(struct persistent_ram_zone *prz, size_t a)
-{
- int old;
- int new;
-
- do {
- old = atomic_read(&prz->buffer->start);
- new = old + a;
- while (unlikely(new >= prz->buffer_size))
- new -= prz->buffer_size;
- } while (atomic_cmpxchg(&prz->buffer->start, old, new) != old);
-
- return old;
-}
-
-/* increase the size counter until it hits the max size */
-static void buffer_size_add_atomic(struct persistent_ram_zone *prz, size_t a)
-{
- size_t old;
- size_t new;
-
- if (atomic_read(&prz->buffer->size) == prz->buffer_size)
- return;
-
- do {
- old = atomic_read(&prz->buffer->size);
- new = old + a;
- if (new > prz->buffer_size)
- new = prz->buffer_size;
- } while (atomic_cmpxchg(&prz->buffer->size, old, new) != old);
-}
-
static DEFINE_RAW_SPINLOCK(buffer_lock);
/* increase and wrap the start pointer, returning the old value */
-static size_t buffer_start_add_locked(struct persistent_ram_zone *prz, size_t a)
+static size_t buffer_start_add(struct persistent_ram_zone *prz, size_t a)
{
int old;
int new;
@@ -101,7 +68,7 @@ static size_t buffer_start_add_locked(struct persistent_ram_zone *prz, size_t a)
}
/* increase the size counter until it hits the max size */
-static void buffer_size_add_locked(struct persistent_ram_zone *prz, size_t a)
+static void buffer_size_add(struct persistent_ram_zone *prz, size_t a)
{
size_t old;
size_t new;
@@ -122,9 +89,6 @@ exit:
raw_spin_unlock_irqrestore(&buffer_lock, flags);
}
-static size_t (*buffer_start_add)(struct persistent_ram_zone *, size_t) = buffer_start_add_atomic;
-static void (*buffer_size_add)(struct persistent_ram_zone *, size_t) = buffer_size_add_atomic;
-
static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz,
uint8_t *data, size_t len, uint8_t *ecc)
{
@@ -426,9 +390,6 @@ static void *persistent_ram_iomap(phys_addr_t start, size_t size,
return NULL;
}
- buffer_start_add = buffer_start_add_locked;
- buffer_size_add = buffer_size_add_locked;
-
if (memtype)
va = ioremap(start, size);
else
--
2.8.0.rc2.1.gbe9624a
--
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