Messages in this thread Patch in this message | | | From | Rusty Russell <> | Date | Thu, 05 Mar 2009 17:27:23 +1030 | Subject | [PATCH 9/10] work_on_cpu: use on drivers/firmware/dcdbas.c |
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Impact: don't play with current's cpumask
It's generally a very bad idea to mug some process's cpumask: it could legitimately and reasonably be changed by root, which could break us (if done before our code) or them (if we restore the wrong value).
So we use work_on_cpu instead of cpumask games.
Note one subtle change. If we can't get to CPU 0 for some reason, the return will be -EINVAL not -EBUSY. We could fix this in the caller? ie:
return work_on_cpu(0, generate_smi, smi_cmd) == 0 ? 0 : -EBUSY;
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Cc: Matthew Garrett <mjg59@srcf.ucam.org> Cc: Matt Domsch <Matt_Domsch@dell.com> Cc: Douglas_Warzecha@dell.com --- drivers/firmware/dcdbas.c | 46 +++++++++++++++++++--------------------------- 1 file changed, 19 insertions(+), 27 deletions(-)
diff --git a/drivers/firmware/dcdbas.c b/drivers/firmware/dcdbas.c --- a/drivers/firmware/dcdbas.c +++ b/drivers/firmware/dcdbas.c @@ -237,31 +237,9 @@ static ssize_t host_control_on_shutdown_ return count; } -/** - * dcdbas_smi_request: generate SMI request - * - * Called with smi_data_lock. - */ -int dcdbas_smi_request(struct smi_cmd *smi_cmd) +static long generate_smi(void *_smi_cmd) { - cpumask_t old_mask; - int ret = 0; - - if (smi_cmd->magic != SMI_CMD_MAGIC) { - dev_info(&dcdbas_pdev->dev, "%s: invalid magic value\n", - __func__); - return -EBADR; - } - - /* SMI requires CPU 0 */ - old_mask = current->cpus_allowed; - set_cpus_allowed_ptr(current, &cpumask_of_cpu(0)); - if (smp_processor_id() != 0) { - dev_dbg(&dcdbas_pdev->dev, "%s: failed to get CPU 0\n", - __func__); - ret = -EBUSY; - goto out; - } + struct smi_cmd *smi_cmd = _smi_cmd; /* generate SMI */ asm volatile ( @@ -273,10 +251,24 @@ int dcdbas_smi_request(struct smi_cmd *s "c" (smi_cmd->ecx) : "memory" ); + return 0; +} -out: - set_cpus_allowed_ptr(current, &old_mask); - return ret; +/** + * dcdbas_smi_request: generate SMI request + * + * Called with smi_data_lock. + */ +int dcdbas_smi_request(struct smi_cmd *smi_cmd) +{ + if (smi_cmd->magic != SMI_CMD_MAGIC) { + dev_info(&dcdbas_pdev->dev, "%s: invalid magic value\n", + __func__); + return -EBADR; + } + + /* SMI requires CPU 0 */ + return work_on_cpu(0, generate_smi, smi_cmd); } /**
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