net: encx24j600: Fix invalid logic in reading of MISTAT register

stable inclusion
from stable-v5.10.159
commit 3d3b30718ae3d651a786eba4ea1ba52dc2941397
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7NTXH

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3d3b30718ae3d651a786eba4ea1ba52dc2941397

--------------------------------

[ Upstream commit 25f427ac ]

A loop for reading MISTAT register continues while regmap_read() fails
and (mistat & BUSY), but if regmap_read() fails a value of mistat is
undefined.

The patch proposes to check for BUSY flag only when regmap_read()
succeed. Compile test only.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: d70e5326 ("net: Microchip encx24j600 driver")
Signed-off-by: NValentina Goncharenko <goncharenko.vp@ispras.ru>
Reviewed-by: NPavan Chebbi <pavan.chebbi@broadcom.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: Nsanglipeng <sanglipeng1@jd.com>

drivers/net/ethernet/microchip/encx24j600-regmap.c

@@ -359,7 +359,7 @@ static int regmap_encx24j600_phy_reg_read(void *context, unsigned int reg,
 		goto err_out;
 
 	usleep_range(26, 100);
-	while (((ret = regmap_read(ctx->regmap, MISTAT, &mistat)) != 0) &&
+	while (((ret = regmap_read(ctx->regmap, MISTAT, &mistat)) == 0) &&
 	       (mistat & BUSY))
 		cpu_relax();
 
@@ -397,7 +397,7 @@ static int regmap_encx24j600_phy_reg_write(void *context, unsigned int reg,
 		goto err_out;
 
 	usleep_range(26, 100);
-	while (((ret = regmap_read(ctx->regmap, MISTAT, &mistat)) != 0) &&
+	while (((ret = regmap_read(ctx->regmap, MISTAT, &mistat)) == 0) &&
 	       (mistat & BUSY))
 		cpu_relax();