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net: ethernet: arc: emac: quiesce interrupts before requesting IRQ

Normal RX/TX interrupts are enabled later, in arc_emac_open(), so probe
should not see interrupt delivery in the usual case. However, hardware may
still present stale or latched interrupt status left by firmware or the
bootloader.

If probe later unwinds after devm_request_irq() has installed the handler,
such a stale interrupt can still reach arc_emac_intr() during teardown and
race with release of the associated net_device.

Avoid that window by putting the device into a known quiescent state before
requesting the IRQ: disable all EMAC interrupt sources and clear any
pending EMAC interrupt status bits. This keeps the change hardware-focused
and minimal, while preventing spurious IRQ delivery from leftover state.

Fixes: e4f2379db6c6 ("ethernet/arc/arc_emac - Add new driver")
Cc: stable@vger.kernel.org
Signed-off-by: Fan Wu <fanwu01@zju.edu.cn>
Link: https://patch.msgid.link/20260309132409.584966-1-fanwu01@zju.edu.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

authored by

Fan Wu and committed by
Jakub Kicinski 2503d08f 28b22528

+11
+11
drivers/net/ethernet/arc/emac_main.c
··· 934 934 /* Set poll rate so that it polls every 1 ms */ 935 935 arc_reg_set(priv, R_POLLRATE, clock_frequency / 1000000); 936 936 937 + /* 938 + * Put the device into a known quiescent state before requesting 939 + * the IRQ. Clear only EMAC interrupt status bits here; leave the 940 + * MDIO completion bit alone and avoid writing TXPL_MASK, which is 941 + * used to force TX polling rather than acknowledge interrupts. 942 + */ 943 + arc_reg_set(priv, R_ENABLE, 0); 944 + arc_reg_set(priv, R_STATUS, RXINT_MASK | TXINT_MASK | ERR_MASK | 945 + TXCH_MASK | MSER_MASK | RXCR_MASK | 946 + RXFR_MASK | RXFL_MASK); 947 + 937 948 ndev->irq = irq; 938 949 dev_info(dev, "IRQ is %d\n", ndev->irq); 939 950