Messages in this thread Patch in this message | | | Subject | [PATCH v2 2/3] hvc_init(): Enforce one-time initialization. | From | Miche Baker-Harvey <> | Date | Tue, 08 Nov 2011 11:29:27 -0800 |
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hvc_init() must only be called once, and no thread should continue with hvc_alloc() until after initialization is complete. The original code does not enforce either of these requirements. A new mutex limits entry to hvc_init() to a single thread, and blocks all later comers until it has completed.
This patch fixes multiple crash symptoms.
Signed-off-by: Miche Baker-Harvey <miche@google.com> --- drivers/tty/hvc/hvc_console.c | 13 +++++++++++-- 1 files changed, 11 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/hvc/hvc_console.c b/drivers/tty/hvc/hvc_console.c index b6b2d18..09a6159 100644 --- a/drivers/tty/hvc/hvc_console.c +++ b/drivers/tty/hvc/hvc_console.c @@ -29,8 +29,9 @@ #include <linux/kernel.h> #include <linux/kthread.h> #include <linux/list.h> -#include <linux/module.h> #include <linux/major.h> +#include <linux/module.h> +#include <linux/mutex.h> #include <linux/sysrq.h> #include <linux/tty.h> #include <linux/tty_flip.h> @@ -84,6 +85,10 @@ static LIST_HEAD(hvc_structs); * list traversal. */ static DEFINE_SPINLOCK(hvc_structs_lock); +/* + * only one task does allocation at a time. + */ +static DEFINE_MUTEX(hvc_ports_mutex); /* * This value is used to assign a tty->index value to a hvc_struct based @@ -825,11 +830,15 @@ struct hvc_struct *hvc_alloc(uint32_t vtermno, int data, int i; /* We wait until a driver actually comes along */ + mutex_lock(&hvc_ports_mutex); if (!hvc_driver) { int err = hvc_init(); - if (err) + if (err) { + mutex_unlock(&hvc_ports_mutex); return ERR_PTR(err); + } } + mutex_unlock(&hvc_ports_mutex); hp = kzalloc(ALIGN(sizeof(*hp), sizeof(long)) + outbuf_size, GFP_KERNEL);
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