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pstore: Allow prz to control need for locking

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In preparation of not locking at all for certain buffers depending on if
there's contention, make locking optional depending on the initialization
of the prz.

Signed-off-by: Joel Fernandes <joelaf@google.com>
[kees: moved locking flag into prz instead of via caller arguments]
Signed-off-by: Kees Cook <keescook@chromium.org>
This commit is contained in:
Joel Fernandes 2016-10-20 00:34:01 -07:00 committed by Kees Cook
parent d8991f51e5
commit 663deb4788
3 changed files with 27 additions and 12 deletions
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5
fs/pstore/ram.c
View File

@ -432,7 +432,7 @@ static int ramoops_init_przs(struct device *dev, struct ramoops_context *cxt,
for (i = 0; i < cxt->max_dump_cnt; i++) {
cxt->przs[i] = persistent_ram_new(*paddr, cxt->record_size, 0,
&cxt->ecc_info,
cxt->memtype);
cxt->memtype, 0);
if (IS_ERR(cxt->przs[i])) {
err = PTR_ERR(cxt->przs[i]);
dev_err(dev, "failed to request mem region (0x%zx@0x%llx): %d\n",
@ -469,7 +469,8 @@ static int ramoops_init_prz(struct device *dev, struct ramoops_context *cxt,
return -ENOMEM;
}
*prz = persistent_ram_new(*paddr, sz, sig, &cxt->ecc_info, cxt->memtype);
*prz = persistent_ram_new(*paddr, sz, sig, &cxt->ecc_info,
cxt->memtype, 0);
if (IS_ERR(*prz)) {
int err = PTR_ERR(*prz);

24
fs/pstore/ram_core.c
View File

@ -53,9 +53,10 @@ static size_t buffer_start_add(struct persistent_ram_zone *prz, size_t a)
{
int old;
int new;
unsigned long flags;
unsigned long flags = 0;
raw_spin_lock_irqsave(&prz->buffer_lock, flags);
if (!(prz->flags & PRZ_FLAG_NO_LOCK))
raw_spin_lock_irqsave(&prz->buffer_lock, flags);
old = atomic_read(&prz->buffer->start);
new = old + a;
@ -63,7 +64,8 @@ static size_t buffer_start_add(struct persistent_ram_zone *prz, size_t a)
new -= prz->buffer_size;
atomic_set(&prz->buffer->start, new);
raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);
if (!(prz->flags & PRZ_FLAG_NO_LOCK))
raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);
return old;
}
@ -73,9 +75,10 @@ static void buffer_size_add(struct persistent_ram_zone *prz, size_t a)
{
size_t old;
size_t new;
unsigned long flags;
unsigned long flags = 0;
raw_spin_lock_irqsave(&prz->buffer_lock, flags);
if (!(prz->flags & PRZ_FLAG_NO_LOCK))
raw_spin_lock_irqsave(&prz->buffer_lock, flags);
old = atomic_read(&prz->buffer->size);
if (old == prz->buffer_size)
@ -87,7 +90,8 @@ static void buffer_size_add(struct persistent_ram_zone *prz, size_t a)
atomic_set(&prz->buffer->size, new);
exit:
raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);
if (!(prz->flags & PRZ_FLAG_NO_LOCK))
raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);
}
static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz,
@ -463,7 +467,8 @@ static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size,
}
static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig,
struct persistent_ram_ecc_info *ecc_info)
struct persistent_ram_ecc_info *ecc_info,
unsigned long flags)
{
int ret;
@ -492,6 +497,7 @@ static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig,
prz->buffer->sig = sig;
persistent_ram_zap(prz);
prz->buffer_lock = __RAW_SPIN_LOCK_UNLOCKED(buffer_lock);
prz->flags = flags;
return 0;
}
@ -516,7 +522,7 @@ void persistent_ram_free(struct persistent_ram_zone *prz)
struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
u32 sig, struct persistent_ram_ecc_info *ecc_info,
unsigned int memtype)
unsigned int memtype, u32 flags)
{
struct persistent_ram_zone *prz;
int ret = -ENOMEM;
@ -531,7 +537,7 @@ struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
if (ret)
goto err;
ret = persistent_ram_post_init(prz, sig, ecc_info);
ret = persistent_ram_post_init(prz, sig, ecc_info, flags);
if (ret)
goto err;

10
include/linux/pstore_ram.h
View File

@ -24,6 +24,13 @@
#include <linux/list.h>
#include <linux/types.h>
/*
* Choose whether access to the RAM zone requires locking or not. If a zone
* can be written to from different CPUs like with ftrace for example, then
* PRZ_FLAG_NO_LOCK is used. For all other cases, locking is required.
*/
#define PRZ_FLAG_NO_LOCK BIT(0)
struct persistent_ram_buffer;
struct rs_control;
@ -40,6 +47,7 @@ struct persistent_ram_zone {
void *vaddr;
struct persistent_ram_buffer *buffer;
size_t buffer_size;
u32 flags;
raw_spinlock_t buffer_lock;
/* ECC correction */
@ -56,7 +64,7 @@ struct persistent_ram_zone {
struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
u32 sig, struct persistent_ram_ecc_info *ecc_info,
unsigned int memtype);
unsigned int memtype, u32 flags);
void persistent_ram_free(struct persistent_ram_zone *prz);
void persistent_ram_zap(struct persistent_ram_zone *prz);