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authorGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-05-15 10:20:16 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-05-15 10:20:16 +0200
commit2c3266e8829eb5a611a08cddca97f79c05ed28db (patch)
treeb7aaa09c1ee1f738acd83b9a46ae2d135f89b22c /0008-tty-n_r3964-don-t-hand-roll-a-reference-count.patch
parentcf6fd4d72fe78061c68af7a241387ec2d26dc161 (diff)
downloadpatches-2c3266e8829eb5a611a08cddca97f79c05ed28db.tar.gz
tty patches added
Diffstat (limited to '0008-tty-n_r3964-don-t-hand-roll-a-reference-count.patch')
-rw-r--r--0008-tty-n_r3964-don-t-hand-roll-a-reference-count.patch160
1 files changed, 160 insertions, 0 deletions
diff --git a/0008-tty-n_r3964-don-t-hand-roll-a-reference-count.patch b/0008-tty-n_r3964-don-t-hand-roll-a-reference-count.patch
new file mode 100644
index 00000000000000..0fd59803294b63
--- /dev/null
+++ b/0008-tty-n_r3964-don-t-hand-roll-a-reference-count.patch
@@ -0,0 +1,160 @@
+From 6e885d94ba582aec3e689d94b3b2deb3570a5e06 Mon Sep 17 00:00:00 2001
+From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+Date: Thu, 24 Jan 2019 16:44:28 +0100
+Subject: [PATCH 08/15] tty: n_r3964: don't hand-roll a reference count
+
+rx_block_header had a "locks" variable that was trying to be a reference
+count on the header. When it would drop to zero, the memory would be
+freed. Convert this to be a kref instead to handle the housekeeping for
+doing reference counting properly.
+
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ drivers/tty/n_r3964.c | 61 ++++++++++++++++++++-----------------------
+ 1 file changed, 28 insertions(+), 33 deletions(-)
+
+diff --git a/drivers/tty/n_r3964.c b/drivers/tty/n_r3964.c
+index 8275fb905aeb..a79c8d485030 100644
+--- a/drivers/tty/n_r3964.c
++++ b/drivers/tty/n_r3964.c
+@@ -26,6 +26,7 @@
+ #include <linux/param.h>
+ #include <linux/poll.h>
+ #include <linux/init.h>
++#include <linux/kref.h>
+ #include <linux/uaccess.h>
+ #include <uapi/linux/n_r3964.h>
+
+@@ -131,8 +132,9 @@ struct rx_block_header {
+ unsigned int length; /* length in chars without header */
+ unsigned char *data; /* usually data is located immediately
+ * behind this struct */
+- unsigned int locks; /* only used in rx_buffer */
+ struct list_head node;
++ struct kref kref;
++ struct r3964_info *info;
+ };
+
+ /* Header of received block in tx_buf: */
+@@ -200,8 +202,7 @@ static void add_msg(struct r3964_client_info *pClient, int msg_id, int arg,
+ int error_code, struct rx_block_header *pBlock);
+ static struct r3964_message *remove_msg(struct r3964_info *pInfo,
+ struct r3964_client_info *pClient);
+-static void remove_client_block(struct r3964_info *pInfo,
+- struct r3964_client_info *pClient);
++static void remove_client_block(struct r3964_client_info *pClient);
+
+ static int r3964_open(struct tty_struct *tty);
+ static void r3964_close(struct tty_struct *tty);
+@@ -357,28 +358,28 @@ static void add_rx_queue(struct r3964_info *pInfo,
+ spin_unlock_irqrestore(&pInfo->lock, flags);
+ }
+
+-static void remove_from_rx_queue(struct r3964_info *pInfo,
+- struct rx_block_header *pHeader)
++static void remove_from_rx_queue(struct kref *kref)
+ {
+- struct rx_block_header *pFind, *tmp;
++ struct rx_block_header *header, *find;
++ struct r3964_info *info;
+ unsigned long flags;
+
+- if (pHeader == NULL)
+- return;
++ header = container_of(kref, struct rx_block_header, kref);
++ info = header->info;
+
+- spin_lock_irqsave(&pInfo->lock, flags);
+- list_for_each_entry_safe(pFind, tmp, &pInfo->rx_blocks, node) {
+- if (pFind == pHeader) {
++ spin_lock_irqsave(&info->lock, flags);
++ list_for_each_entry(find, &info->rx_blocks, node) {
++ if (find == header) {
+ /* Got it. */
+- list_del(&pFind->node);
+- pInfo->blocks_in_rx_queue--;
++ list_del(&find->node);
++ info->blocks_in_rx_queue--;
+ goto exit;
+ }
+ }
+ exit:
+- spin_unlock_irqrestore(&pInfo->lock, flags);
++ spin_unlock_irqrestore(&info->lock, flags);
+
+- kfree(pHeader);
++ kfree(header);
+ }
+
+ static void put_char(struct r3964_info *pInfo, unsigned char ch)
+@@ -540,7 +541,8 @@ static void on_receive_block(struct r3964_info *pInfo)
+
+ pBlock->length = length;
+ pBlock->data = ((unsigned char *)pBlock) + sizeof(*pBlock);
+- pBlock->locks = 0;
++ pBlock->info = pInfo;
++ kref_init(&pBlock->kref);
+ INIT_LIST_HEAD(&pBlock->node);
+
+ memcpy(pBlock->data, pInfo->rx_buf, length);
+@@ -855,7 +857,7 @@ static int read_telegram(struct r3964_info *pInfo, struct pid *pid,
+ if (copy_to_user(buf, block->data, block->length))
+ return -EFAULT;
+
+- remove_client_block(pInfo, pClient);
++ remove_client_block(pClient);
+ return block->length;
+ }
+
+@@ -894,9 +896,9 @@ static void add_msg(struct r3964_client_info *pClient, int msg_id, int arg,
+
+ pClient->msg_count++;
+
+- if (pBlock != NULL) {
+- pBlock->locks++;
+- }
++ if (pBlock != NULL)
++ kref_get(&pBlock->kref);
++
+ spin_unlock_irqrestore(&pClient->lock, flags);
+ } else {
+ if ((pClient->last_msg->msg_id == R3964_MSG_ACK)
+@@ -935,7 +937,7 @@ static struct r3964_message *remove_msg(struct r3964_info *pInfo,
+
+ pClient->msg_count--;
+ if (pMsg->block) {
+- remove_client_block(pInfo, pClient);
++ remove_client_block(pClient);
+ pClient->next_block_to_read = pMsg->block;
+ }
+ spin_unlock_irqrestore(&pClient->lock, flags);
+@@ -943,21 +945,14 @@ static struct r3964_message *remove_msg(struct r3964_info *pInfo,
+ return pMsg;
+ }
+
+-static void remove_client_block(struct r3964_info *pInfo,
+- struct r3964_client_info *pClient)
++static void remove_client_block(struct r3964_client_info *client)
+ {
+ struct rx_block_header *block;
+
+- TRACE_PS("remove_client_block PID %d", pid_nr(pClient->pid));
+-
+- block = pClient->next_block_to_read;
+- if (block) {
+- block->locks--;
+- if (block->locks == 0) {
+- remove_from_rx_queue(pInfo, block);
+- }
+- }
+- pClient->next_block_to_read = NULL;
++ block = client->next_block_to_read;
++ if (block)
++ kref_put(&block->kref, remove_from_rx_queue);
++ client->next_block_to_read = NULL;
+ }
+
+ /*************************************************************
+--
+2.21.0
+
generated by cgit 1.2.3-korg (git 2.43.0) at 2026-03-01 17:43:04 +0000