spi: spl022: fix sleeping in interrupt context

Merge series from Nam Cao <namcao@linutronix.de>:

While running the spl022, I got the following warning:
BUG: sleeping function called from invalid context at drivers/spi/spi.c:1428

This is because between spi transfers, spi_transfer_delay_exec() (who
may sleep if the delay is >10us) is called in interrupt context. This is
a problem for anyone who runs this driver and need more than 10us delay.

Patch 1 adds an error reporting mechanism, needed by patch 2 who switch
to use the default spi_transfer_one_message(), which fix the problem.

The series is tested with polling transfer mode and interrupt transfer
mode. I can't test the DMA mode, so some help testing here is very
appreciated.

1 files changed, 11 insertions, 3 deletions

diff --git a/fs/libfs.c b/fs/libfs.c
index e9440d55073c..c2aa6fd4795c 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -399,6 +399,8 @@ static loff_t offset_dir_llseek(struct file *file, loff_t offset, int whence)
 		return -EINVAL;
 	}
 
+	/* In this case, ->private_data is protected by f_pos_lock */
+	file->private_data = NULL;
 	return vfs_setpos(file, offset, U32_MAX);
 }
 
@@ -428,7 +430,7 @@ static bool offset_dir_emit(struct dir_context *ctx, struct dentry *dentry)
 			  inode->i_ino, fs_umode_to_dtype(inode->i_mode));
 }
 
-static void offset_iterate_dir(struct inode *inode, struct dir_context *ctx)
+static void *offset_iterate_dir(struct inode *inode, struct dir_context *ctx)
 {
 	struct offset_ctx *so_ctx = inode->i_op->get_offset_ctx(inode);
 	XA_STATE(xas, &so_ctx->xa, ctx->pos);
@@ -437,7 +439,7 @@ static void offset_iterate_dir(struct inode *inode, struct dir_context *ctx)
 	while (true) {
 		dentry = offset_find_next(&xas);
 		if (!dentry)
-			break;
+			return ERR_PTR(-ENOENT);
 
 		if (!offset_dir_emit(ctx, dentry)) {
 			dput(dentry);
@@ -447,6 +449,7 @@ static void offset_iterate_dir(struct inode *inode, struct dir_context *ctx)
 		dput(dentry);
 		ctx->pos = xas.xa_index + 1;
 	}
+	return NULL;
 }
 
 /**
@@ -479,7 +482,12 @@ static int offset_readdir(struct file *file, struct dir_context *ctx)
 	if (!dir_emit_dots(file, ctx))
 		return 0;
 
-	offset_iterate_dir(d_inode(dir), ctx);
+	/* In this case, ->private_data is protected by f_pos_lock */
+	if (ctx->pos == 2)
+		file->private_data = NULL;
+	else if (file->private_data == ERR_PTR(-ENOENT))
+		return 0;
+	file->private_data = offset_iterate_dir(d_inode(dir), ctx);
 	return 0;
 }