From: Grazvydas Ignotas <notasas@gmail.com>
Date: Wed, 20 Mar 2013 17:12:05 +0000 (+0200)
Subject: Revert "staging: android: persistent_ram: make persistent_ram_write atomic"
X-Git-Tag: sz_154~6
X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=commitdiff_plain;h=a409a7e2a635a8ade7adb23981993200a82e547e

Revert "staging: android: persistent_ram: make persistent_ram_write atomic"

This reverts commit 9ec12b4106cc43d27db79ef621afeaf8a430c842
(this atomic stuff causes data abort on OMAP3?)

Conflicts:

	drivers/staging/android/persistent_ram.c
---

diff --git a/drivers/staging/android/persistent_ram.c b/drivers/staging/android/persistent_ram.c
index 8d8c1e33e0ff..86f0837a531f 100644
--- a/drivers/staging/android/persistent_ram.c
+++ b/drivers/staging/android/persistent_ram.c
@@ -27,8 +27,8 @@
 
 struct persistent_ram_buffer {
 	uint32_t    sig;
-	atomic_t    start;
-	atomic_t    size;
+	uint32_t    start;
+	uint32_t    size;
 	uint8_t     data[0];
 };
 
@@ -36,66 +36,6 @@ struct persistent_ram_buffer {
 
 static __initdata LIST_HEAD(persistent_ram_list);
 
-static inline size_t buffer_size(struct persistent_ram_zone *prz)
-{
-	return atomic_read(&prz->buffer->size);
-}
-
-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 inline size_t buffer_start_add(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 inline void buffer_size_add(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);
-}
-
-/* increase the size counter, retuning an error if it hits the max size */
-static inline ssize_t buffer_size_add_clamp(struct persistent_ram_zone *prz,
-	size_t a)
-{
-	size_t old;
-	size_t new;
-
-	do {
-		old = atomic_read(&prz->buffer->size);
-		new = old + a;
-		if (new > prz->buffer_size)
-			return -ENOMEM;
-	} while (atomic_cmpxchg(&prz->buffer->size, old, new) != old);
-
-	return 0;
-}
-
 static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz,
 	uint8_t *data, size_t len, uint8_t *ecc)
 {
@@ -122,7 +62,7 @@ static int persistent_ram_decode_rs8(struct persistent_ram_zone *prz,
 }
 
 static void notrace persistent_ram_update_ecc(struct persistent_ram_zone *prz,
-	unsigned int start, unsigned int count)
+	unsigned int count)
 {
 	struct persistent_ram_buffer *buffer = prz->buffer;
 	uint8_t *buffer_end = buffer->data + prz->buffer_size;
@@ -135,16 +75,16 @@ static void notrace persistent_ram_update_ecc(struct persistent_ram_zone *prz,
 	if (!prz->ecc)
 		return;
 
-	block = buffer->data + (start & ~(ecc_block_size - 1));
-	par = prz->par_buffer + (start / ecc_block_size) * prz->ecc_size;
-
+	block = buffer->data + (buffer->start & ~(ecc_block_size - 1));
+	par = prz->par_buffer +
+	      (buffer->start / ecc_block_size) * prz->ecc_size;
 	do {
 		if (block + ecc_block_size > buffer_end)
 			size = buffer_end - block;
 		persistent_ram_encode_rs8(prz, block, size, par);
 		block += ecc_block_size;
 		par += ecc_size;
-	} while (block < buffer->data + start + count);
+	} while (block < buffer->data + buffer->start + count);
 }
 
 static void persistent_ram_update_header_ecc(struct persistent_ram_zone *prz)
@@ -169,7 +109,7 @@ static void persistent_ram_ecc_old(struct persistent_ram_zone *prz)
 
 	block = buffer->data;
 	par = prz->par_buffer;
-	while (block < buffer->data + buffer_size(prz)) {
+	while (block < buffer->data + buffer->size) {
 		int numerr;
 		int size = prz->ecc_block_size;
 		if (block + size > buffer->data + prz->buffer_size)
@@ -259,33 +199,34 @@ ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
 }
 
 static void notrace persistent_ram_update(struct persistent_ram_zone *prz,
-	const void *s, unsigned int start, unsigned int count)
+	const void *s, unsigned int count)
 {
 	struct persistent_ram_buffer *buffer = prz->buffer;
-	memcpy(buffer->data + start, s, count);
-	persistent_ram_update_ecc(prz, start, count);
+	memcpy(buffer->data + buffer->start, s, count);
+	persistent_ram_update_ecc(prz, count);
 }
 
 static void __init
 persistent_ram_save_old(struct persistent_ram_zone *prz)
 {
 	struct persistent_ram_buffer *buffer = prz->buffer;
-	size_t size = buffer_size(prz);
-	size_t start = buffer_start(prz);
+	size_t old_log_size = buffer->size;
 	char *dest;
 
 	persistent_ram_ecc_old(prz);
 
-	dest = kmalloc(size, GFP_KERNEL);
+	dest = kmalloc(old_log_size, GFP_KERNEL);
 	if (dest == NULL) {
 		pr_err("persistent_ram: failed to allocate buffer\n");
 		return;
 	}
 
 	prz->old_log = dest;
-	prz->old_log_size = size;
-	memcpy(prz->old_log, &buffer->data[start], size - start);
-	memcpy(prz->old_log + size - start, &buffer->data[0], start);
+	prz->old_log_size = old_log_size;
+	memcpy(prz->old_log,
+	       &buffer->data[buffer->start], buffer->size - buffer->start);
+	memcpy(prz->old_log + buffer->size - buffer->start,
+	       &buffer->data[0], buffer->start);
 }
 
 int notrace persistent_ram_write(struct persistent_ram_zone *prz,
@@ -293,26 +234,25 @@ int notrace persistent_ram_write(struct persistent_ram_zone *prz,
 {
 	int rem;
 	int c = count;
-	size_t start;
+	struct persistent_ram_buffer *buffer = prz->buffer;
 
-	if (unlikely(c > prz->buffer_size)) {
+	if (c > prz->buffer_size) {
 		s += c - prz->buffer_size;
 		c = prz->buffer_size;
 	}
-
-	buffer_size_add_clamp(prz, c);
-
-	start = buffer_start_add(prz, c);
-
-	rem = prz->buffer_size - start;
-	if (unlikely(rem < c)) {
-		persistent_ram_update(prz, s, start, rem);
+	rem = prz->buffer_size - buffer->start;
+	if (rem < c) {
+		persistent_ram_update(prz, s, rem);
 		s += rem;
 		c -= rem;
-		start = 0;
+		buffer->start = 0;
+		buffer->size = prz->buffer_size;
 	}
-	persistent_ram_update(prz, s, start, c);
+	persistent_ram_update(prz, s, c);
 
+	buffer->start += c;
+	if (buffer->size < prz->buffer_size)
+		buffer->size += c;
 	persistent_ram_update_header_ecc(prz);
 
 	return count;
@@ -421,25 +361,23 @@ struct persistent_ram_zone *__persistent_ram_init(struct device *dev, bool ecc)
 		goto err;
 
 	if (prz->buffer->sig == PERSISTENT_RAM_SIG) {
-		if (buffer_size(prz) > prz->buffer_size ||
-		    buffer_start(prz) > buffer_size(prz))
-			pr_info("persistent_ram: found existing invalid buffer,"
-				" size %ld, start %ld\n",
-			       buffer_size(prz), buffer_start(prz));
+		if (prz->buffer->size > prz->buffer_size
+		    || prz->buffer->start > prz->buffer->size)
+			pr_info("persistent_ram: found existing invalid buffer, size %d, start %d\n",
+			       prz->buffer->size, prz->buffer->start);
 		else {
-			pr_info("persistent_ram: found existing buffer,"
-				" size %ld, start %ld\n",
-			       buffer_size(prz), buffer_start(prz));
+			pr_info("persistent_ram: found existing buffer, size %d, start %d\n",
+			       prz->buffer->size, prz->buffer->start);
 			persistent_ram_save_old(prz);
 		}
 	} else {
-		pr_info("persistent_ram: no valid data in buffer"
-			" (sig = 0x%08x)\n", prz->buffer->sig);
+		pr_info("persistent_ram: no valid data in buffer (sig = 0x%08x)\n",
+			prz->buffer->sig);
 	}
 
 	prz->buffer->sig = PERSISTENT_RAM_SIG;
-	atomic_set(&prz->buffer->start, 0);
-	atomic_set(&prz->buffer->size, 0);
+	prz->buffer->start = 0;
+	prz->buffer->size = 0;
 
 	return prz;
 err: