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| author | Prasanna S. Panchamukhi <prasannax.s.panchamukhi@intel.com> | 2010-04-14 01:35:58 +0200 |
|---|---|---|
| committer | Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com> | 2010-05-11 23:08:23 +0200 |
| commit | d11a6e4495ee1fbb38b59bc88d49d050d3736929 (patch) | |
| tree | 08afc7d7909dc451878f2ec04747071e2999e6e4 /drivers/net/wimax/i2400m/i2400m.h | |
| parent | wimax/i2400m: increase tx queue length from 5 to 20 [v1] (diff) | |
| download | linux-d11a6e4495ee1fbb38b59bc88d49d050d3736929.tar.xz linux-d11a6e4495ee1fbb38b59bc88d49d050d3736929.zip | |
wimax i2400m: fix race condition while accessing rx_roq by using kref count
This patch fixes the race condition when one thread tries to destroy
the memory allocated for rx_roq, while another thread still happen
to access rx_roq.
Such a race condition occurs when i2400m-sdio kernel module gets
unloaded, destroying the memory allocated for rx_roq while rx_roq
is accessed by i2400m_rx_edata(), as explained below:
$thread1 $thread2
$ void i2400m_rx_edata() $
$Access rx_roq[] $
$roq = &i2400m->rx_roq[ro_cin] $
$ i2400m_roq_[reset/queue/update_ws] $
$ $ void i2400m_rx_release();
$ $kfree(rx->roq);
$ $rx->roq = NULL;
$Oops! rx_roq is NULL
This patch fixes the race condition using refcount approach.
Signed-off-by: Prasanna S. Panchamukhi <prasannax.s.panchamukhi@intel.com>
Diffstat (limited to 'drivers/net/wimax/i2400m/i2400m.h')
| -rw-r--r-- | drivers/net/wimax/i2400m/i2400m.h | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/drivers/net/wimax/i2400m/i2400m.h b/drivers/net/wimax/i2400m/i2400m.h index 7a9c2c5b25cb..b8c7dbfead49 100644 --- a/drivers/net/wimax/i2400m/i2400m.h +++ b/drivers/net/wimax/i2400m/i2400m.h @@ -412,7 +412,7 @@ struct i2400m_barker_db; * * @tx_size_max: biggest TX message sent. * - * @rx_lock: spinlock to protect RX members + * @rx_lock: spinlock to protect RX members and rx_roq_refcount. * * @rx_pl_num: total number of payloads received * @@ -436,6 +436,10 @@ struct i2400m_barker_db; * delivered. Then the driver can release them to the host. See * drivers/net/i2400m/rx.c for details. * + * @rx_roq_refcount: refcount rx_roq. This refcounts any access to + * rx_roq thus preventing rx_roq being destroyed when rx_roq + * is being accessed. rx_roq_refcount is protected by rx_lock. + * * @rx_reports: reports received from the device that couldn't be * processed because the driver wasn't still ready; when ready, * they are pulled from here and chewed. @@ -597,10 +601,12 @@ struct i2400m { tx_num, tx_size_acc, tx_size_min, tx_size_max; /* RX stuff */ - spinlock_t rx_lock; /* protect RX state */ + /* protect RX state and rx_roq_refcount */ + spinlock_t rx_lock; unsigned rx_pl_num, rx_pl_max, rx_pl_min, rx_num, rx_size_acc, rx_size_min, rx_size_max; - struct i2400m_roq *rx_roq; /* not under rx_lock! */ + struct i2400m_roq *rx_roq; /* access is refcounted */ + struct kref rx_roq_refcount; /* refcount access to rx_roq */ u8 src_mac_addr[ETH_HLEN]; struct list_head rx_reports; /* under rx_lock! */ struct work_struct rx_report_ws; |