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Subject[PATCH 2/4] firmware loader: fix one reqeust_firmware race
Date
Several loading requests may be pending on one same
firmware buf, and this patch moves fw_map_pages_buf()
before complete_all(&fw_buf->completion) and let all
requests see the mapped 'buf->data' once the loading
is completed.

Signed-off-by: Ming Lei <ming.lei@canonical.com>
---
drivers/base/firmware_class.c | 32 ++++++++++++++++++++------------
1 file changed, 20 insertions(+), 12 deletions(-)

diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index d06a8d0..f288251 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -423,6 +423,18 @@ static void firmware_free_data(const struct firmware *fw)
#ifndef PAGE_KERNEL_RO
#define PAGE_KERNEL_RO PAGE_KERNEL
#endif
+
+/* one pages buffer should be mapped/unmapped only once */
+static int fw_map_pages_buf(struct firmware_buf *buf)
+{
+ if (buf->data)
+ vunmap(buf->data);
+ buf->data = vmap(buf->pages, buf->nr_pages, 0, PAGE_KERNEL_RO);
+ if (!buf->data)
+ return -ENOMEM;
+ return 0;
+}
+
/**
* firmware_loading_store - set value in the 'loading' control file
* @dev: device pointer
@@ -467,6 +479,14 @@ static ssize_t firmware_loading_store(struct device *dev,
if (test_bit(FW_STATUS_LOADING, &fw_buf->status)) {
set_bit(FW_STATUS_DONE, &fw_buf->status);
clear_bit(FW_STATUS_LOADING, &fw_buf->status);
+
+ /*
+ * Several loading requests may be pending on
+ * one same firmware buf, so let all requests
+ * see the mapped 'buf->data' once the loading
+ * is completed.
+ * */
+ fw_map_pages_buf(fw_buf);
complete_all(&fw_buf->completion);
break;
}
@@ -670,15 +690,6 @@ exit:
return fw_priv;
}

-/* one pages buffer is mapped/unmapped only once */
-static int fw_map_pages_buf(struct firmware_buf *buf)
-{
- buf->data = vmap(buf->pages, buf->nr_pages, 0, PAGE_KERNEL_RO);
- if (!buf->data)
- return -ENOMEM;
- return 0;
-}
-
/* store the pages buffer info firmware from buf */
static void fw_set_page_data(struct firmware_buf *buf, struct firmware *fw)
{
@@ -884,9 +895,6 @@ static int _request_firmware_load(struct firmware_priv *fw_priv, bool uevent,
if (!retval && f_dev->parent)
fw_add_devm_name(f_dev->parent, buf->fw_id);

- if (!retval)
- retval = fw_map_pages_buf(buf);
-
/*
* After caching firmware image is started, let it piggyback
* on request firmware.
--
1.7.9.5


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