[PATCH RFC 10/27] genirq/proc: let procfs copy in the affinity masks

[Christian Brauner]

Implement ->proc_write_buf() for smp_affinity, smp_affinity_list and
default_smp_affinity so procfs copies in what is written before it pins
the entry, and parse the masks from that copy. A list of CPUs can be
longer than a page on large machines, so the files take as much as
memdup_user_nul() could copy in before. Anything larger fails with
-EINVAL instead of -ENOMEM.

Signed-off-by: Christian Brauner (Amutable) <brauner@xxxxxxxxxx>
---
 kernel/irq/proc.c | 27 +++++++++++++++++----------
 1 file changed, 17 insertions(+), 10 deletions(-)

diff --git a/kernel/irq/proc.c b/kernel/irq/proc.c
index aa3d5544cfc1..fe683457a088 100644
--- a/kernel/irq/proc.c
+++ b/kernel/irq/proc.c
@@ -9,6 +9,7 @@
 #include <linux/gfp.h>
 #include <linux/proc_fs.h>
 #include <linux/seq_file.h>
+#include <linux/slab.h>
 #include <linux/interrupt.h>
 #include <linux/kernel.h>
 #include <linux/kernel_stat.h>
@@ -134,8 +135,11 @@ static inline int irq_select_affinity_usr(unsigned int irq)
 }
 #endif
 
+/* lists of CPUs can outgrow a page, take what memdup_user_nul() took */
+#define IRQ_AFFINITY_WRITE_SIZE	(KMALLOC_MAX_SIZE - 1)
+
 static ssize_t write_irq_affinity(int type, struct file *file,
-		const char __user *buffer, size_t count, loff_t *pos)
+		char *buffer, size_t count, loff_t *pos)
 {
 	unsigned int irq = (int)(long)pde_data(file_inode(file));
 	cpumask_var_t new_value;
@@ -148,9 +152,9 @@ static ssize_t write_irq_affinity(int type, struct file *file,
 		return -ENOMEM;
 
 	if (type)
-		err = cpumask_parselist_user(buffer, count, new_value);
+		err = cpulist_parse(buffer, new_value);
 	else
-		err = cpumask_parse_user(buffer, count, new_value);
+		err = cpumask_parse(buffer, new_value);
 	if (err)
 		goto free_cpumask;
 
@@ -177,25 +181,27 @@ free_cpumask:
 }
 
 static ssize_t irq_affinity_proc_write(struct file *file,
-		const char __user *buffer, size_t count, loff_t *pos)
+		char *buffer, size_t count, loff_t *pos)
 {
 	return write_irq_affinity(0, file, buffer, count, pos);
 }
 
 static ssize_t irq_affinity_list_proc_write(struct file *file,
-		const char __user *buffer, size_t count, loff_t *pos)
+		char *buffer, size_t count, loff_t *pos)
 {
 	return write_irq_affinity(1, file, buffer, count, pos);
 }
 
 static const struct proc_ops irq_affinity_proc_ops = {
 	.proc_show	= irq_affinity_proc_show,
-	.proc_write	= irq_affinity_proc_write,
+	.proc_write_buf	= irq_affinity_proc_write,
+	.proc_write_size = IRQ_AFFINITY_WRITE_SIZE,
 };
 
 static const struct proc_ops irq_affinity_list_proc_ops = {
 	.proc_show	= irq_affinity_list_proc_show,
-	.proc_write	= irq_affinity_list_proc_write,
+	.proc_write_buf	= irq_affinity_list_proc_write,
+	.proc_write_size = IRQ_AFFINITY_WRITE_SIZE,
 };
 
 #ifdef CONFIG_GENERIC_IRQ_EFFECTIVE_AFF_MASK
@@ -217,7 +223,7 @@ static int default_affinity_show(struct seq_file *m, void *v)
 }
 
 static ssize_t default_affinity_write(struct file *file,
-		const char __user *buffer, size_t count, loff_t *ppos)
+		char *buffer, size_t count, loff_t *ppos)
 {
 	cpumask_var_t new_value;
 	int err;
@@ -225,7 +231,7 @@ static ssize_t default_affinity_write(struct file *file,
 	if (!zalloc_cpumask_var(&new_value, GFP_KERNEL))
 		return -ENOMEM;
 
-	err = cpumask_parse_user(buffer, count, new_value);
+	err = cpumask_parse(buffer, new_value);
 	if (err)
 		goto out;
 
@@ -249,7 +255,8 @@ out:
 
 static const struct proc_ops default_affinity_proc_ops = {
 	.proc_show	= default_affinity_show,
-	.proc_write	= default_affinity_write,
+	.proc_write_buf	= default_affinity_write,
+	.proc_write_size = IRQ_AFFINITY_WRITE_SIZE,
 };
 
 static int irq_node_proc_show(struct seq_file *m, void *v)

-- 
2.53.0