mfd: Stop setting refcounting pointers in original mfd_cell arrays

Commit 1e29af62f2b285bd18685da93c3ce8c33ca2d1db ("mfd: Add refcounting
support to mfd_cells") had to drop the "const" keyword on the "cell"
parameter of mfd_add_devices(), as it added the refcounting pointers
to the objects of the passed mfd_cell array itself.

However, the mfd core code operates on copies of the mfd_cell objects,
so there's no need to modify the originally passed objects.

Hence, move the setting of the refcounting pointers from mfd_add_devices()
to mfd_platform_add_cell(), where the copy of the mfd_cell objects is made.
mfd_clone_cell() can just pass (a copy of) the original usage_count
pointer.

This allows to make the "cell" parameter of mfd_add_devices() "const"
again, and avoids future race conditions when registering multiple
instances of the same device in parallel.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

diff --git a/drivers/mfd/mfd-core.c b/drivers/mfd/mfd-core.c
index f421586f29fb09b02644ee8b05aa6777fb353835..8736f4539bc0a835eb0a7acbee57209012d06685 100644 (file)
--- a/drivers/mfd/mfd-core.c
+++ b/drivers/mfd/mfd-core.c
@@ -63,7 +63,8 @@ int mfd_cell_disable(struct platform_device *pdev)
 EXPORT_SYMBOL(mfd_cell_disable);
 
 static int mfd_platform_add_cell(struct platform_device *pdev,
-                                const struct mfd_cell *cell)
+                                const struct mfd_cell *cell,
+                                atomic_t *usage_count)
 {
        if (!cell)
                return 0;
@@ -72,11 +73,12 @@ static int mfd_platform_add_cell(struct platform_device *pdev,
        if (!pdev->mfd_cell)
                return -ENOMEM;
 
+       pdev->mfd_cell->usage_count = usage_count;
        return 0;
 }
 
 static int mfd_add_device(struct device *parent, int id,
-                         const struct mfd_cell *cell,
+                         const struct mfd_cell *cell, atomic_t *usage_count,
                          struct resource *mem_base,
                          int irq_base, struct irq_domain *domain)
 {
@@ -115,7 +117,7 @@ static int mfd_add_device(struct device *parent, int id,
                        goto fail_res;
        }
 
-       ret = mfd_platform_add_cell(pdev, cell);
+       ret = mfd_platform_add_cell(pdev, cell, usage_count);
        if (ret)
                goto fail_res;
 
@@ -180,7 +182,7 @@ fail_alloc:
 }
 
 int mfd_add_devices(struct device *parent, int id,
-                   struct mfd_cell *cells, int n_devs,
+                   const struct mfd_cell *cells, int n_devs,
                    struct resource *mem_base,
                    int irq_base, struct irq_domain *domain)
 {
@@ -195,8 +197,7 @@ int mfd_add_devices(struct device *parent, int id,
 
        for (i = 0; i < n_devs; i++) {
                atomic_set(&cnts[i], 0);
-               cells[i].usage_count = &cnts[i];
-               ret = mfd_add_device(parent, id, cells + i, mem_base,
+               ret = mfd_add_device(parent, id, cells + i, cnts + i, mem_base,
                                     irq_base, domain);
                if (ret)
                        break;
@@ -259,8 +260,8 @@ int mfd_clone_cell(const char *cell, const char **clones, size_t n_clones)
        for (i = 0; i < n_clones; i++) {
                cell_entry.name = clones[i];
                /* don't give up if a single call fails; just report error */
-               if (mfd_add_device(pdev->dev.parent, -1, &cell_entry, NULL, 0,
-                                  NULL))
+               if (mfd_add_device(pdev->dev.parent, -1, &cell_entry,
+                                  cell_entry.usage_count, NULL, 0, NULL))
                        dev_err(dev, "failed to create platform device '%s'\n",
                                        clones[i]);
        }

diff --git a/include/linux/mfd/core.h b/include/linux/mfd/core.h
index cebe97ee98b86e1d6f6ef478ddf84693d8486d6b..60ced604664fbfa1ba178a03e000a6a537683756 100644 (file)
--- a/include/linux/mfd/core.h
+++ b/include/linux/mfd/core.h
@@ -98,7 +98,7 @@ static inline const struct mfd_cell *mfd_get_cell(struct platform_device *pdev)
 }
 
 extern int mfd_add_devices(struct device *parent, int id,
-                          struct mfd_cell *cells, int n_devs,
+                          const struct mfd_cell *cells, int n_devs,
                           struct resource *mem_base,
                           int irq_base, struct irq_domain *irq_domain);